**Summary**
Step 2 in prep for pluggable auto-partitioners, remove `regex_metadata`
field from `ElementMetadata`.
**Additional Context**
- "regex-metadata" was an experimental feature that didn't pan out.
- It's implemented by one of the post-partitioning metadata decorators,
so get rid of it as part of the cleanup before consolidating those
decorators.
### Summary
Rip off page_number metadata fields until we have page counting for all
kinds of html files (not just limited to news articles with multiple
`<article>` tag)
### Test
Unit tests
`test_add_chunking_strategy_on_partition_html_respects_multipage` and
`test_add_chunking_strategy_title_on_partition_auto_respects_multipage`
removed since they relay on the `page_number` fields from the SEC html
file - now test moved to mock test for chunk_by_title -> revisit those
tests when we find test file for this
Also changed the element ids from partition outputs for html files -
element id change due to page number change (in element id hashing) ->
todo ticket: update other deterministic element id tests per crag's
comment
---------
Co-authored-by: ryannikolaidis <1208590+ryannikolaidis@users.noreply.github.com>
Co-authored-by: yuming-long <yuming-long@users.noreply.github.com>
**Summary**
The `.section` field in `ElementMetadata` is dead code, possibly a
remainder from a prior iteration of `partition_epub()`. In any case, it
is not populated by any partitioner. Remove it and any code that uses
it.
Minor refactor after conversation with @scanny
Updates docstring and how chunking options are accessed.
`self._kwargs.get()` should only be used in the `lazyproperty`
definition of an instance's attribute. Other calls should use
`self.<attribute>`
**Summary**
Add the actual behavior to populate `.metadata.orig_elements` during
chunking, when so instructed by the `include_orig_elements` option.
**Additional Context**
The underlying structures to support this, namely the
`.metadata.orig_elements` field and the `include_orig_elements` chunking
option, were added in closely prior PRs. This PR adds the behavior to
actually populate that metadata field during chunking when the option is
set.
**Summary**
Add `include_orig_elements: bool = True` as a new chunking option. This
PR does not implement _adding_ original elements to chunks, only
accepting this parameter as a chunking option and assigning `True` to it
as a default value when it is omitted as a keyword argument.
Note this will need to be added in other repositories as well in order
to fully support this new option by all access methods. In particular it
will need to be added in `unstructured-api` in order to become available
via the SDKs.
**Summary**
A pluggable chunking strategy needs its own local set of chunking
options that subclasses a base-class in `unstructured`.
Extract distinct `_ByTitleChunkingOptions` and `_BasicChunkingOptions`
for the existing two chunking strategies and move their
strategy-specific option setting and validation to the respective
subclass.
This was also a good opportunity for us to clean up a few odds and ends
we'd been meaning to.
Might be worth looking at the commits individually as they are cohesive
incremental steps toward the goal.
**Summary**
In order to accommodate customized chunkers other than those directly
provided by `unstructured`, some further modularization is necessary
such that a new chunker can be added as a "plug-in" without modifying
the `unstructured` library code.
This PR is the straightforward refactoring required for this process
like typing changes. There are also some other small changes we've been
meaning to make like making all chunking options accept `None` to
represent their default value so the broad field of callers (e.g.
ingest, unstructured-api, SDK) don't need to determine and set default
values for chunking arguments leading to diverging defaults.
Isolating these "noisy" but easy to accept changes in this preparatory
PR reduces the noise in the more substantive changes to follow.
The text of an oversized chunk is split on an arbitrary character
boundary (mid-word). The `chunk_by_character()` strategy introduces the
idea of allowing the user to specify a separator to use for
chunk-splitting. For `langchain` this is typically "\n\n", "\n", or " ";
blank-line, newline, or word boundaries respectively.
Even if the user is allowed to specify a separator, we must provide
fall-back for when a chunk contains no such character. This can be done
incrementally, like blank-line is preferable to newline, newline is
preferable to word, and word is preferable to arbitrary character.
Further, there is nothing particular to `chunk_by_character()` in
providing such a fall-back text-splitting strategy. It would be
preferable for all strategies to split oversized chunks on even-word
boundaries for example.
Note that while a "blank-line" ("\n\n") may be common in plain text, it
is unlikely to appear in the text of an element because it would have
been interpreted as an element boundary during partitioning.
Add _TextSplitter with basic separator preferences and fall-back and
apply it to chunk-splitting for all strategies. The `by_character`
chunking strategy may enhance this behavior by adding the option for a
user to specify a particular separator suited to their use case.
The `_split_elements_by_title_and_table()` function fulfills the
pre-chunker role for `chunk_by_title()`, but most of its operation is
not strategy-specific and can be reused by other chunking strategies.
Extract `BasePreChunker` and use it as the base class for
`_ByTitlePreChunker` which now only needs to provide the boundary
predicates specific to that strategy.
Many of the classes defined in `unstructured.chunking.title` are
applicable to any chunking strategy and will shortly be used for the
"by-character" chunking strategy as well.
Move these and their tests to `unstructured.chunking.base`.
Along the way, rename `TextPreChunkBuilder` to `PreChunkBuilder` because
it will be generalized in a subsequent PR to also take `Table` elements
such that inter-pre-chunk overlap can be implemented.
Otherwise, no logic changes, just moves.
Chunking options for things like chunk-size are largely independent of
chunking strategy. Further, validating the args and applying defaults
based on call arguments is sophisticated to make its use easy for the
caller. These details distract from what the chunker is actually doing
and would need to be repeated for every chunking strategy if left where
they are.
Extract these settings and the rules governing chunking behavior based
on options into its own immutable object that can be passed to any
component that is subject to optional behavior (pretty much all of
them).
The original naming for the pre-cursor to a chunk in `chunk_by_title()`
was conflated with the idea of how these element subsequences were
bounded (by document-section) for that strategy. I mistakenly picked
that up as a universal concept but in fact no notion of section arises
in the `by_character` or other chunking strategies.
Fix this misconception by using the name `pre-chunk` for this concept
throughout.
`CheckBox` elements get special treatment during chunking. `CheckBox`
does not derive from `Text` and can contribute no text to a chunk. It is
considered "non-combinable" and so is emitted as-is as a chunk of its
own. A consequence of this is it breaks an otherwise contiguous chunk
into two wherever it occurs.
This is problematic, but becomes much more so when overlap is
introduced. Each chunk accepts a "tail" text fragment from its preceding
element and contributes its own tail fragment to the next chunk. These
tails represent the "overlap" between chunks. However, a non-text chunk
can neither accept nor provide a tail-fragment and so interrupts the
overlap. None of the possible solutions are terrific.
Give `Element` a `.text` attribute such that _all_ elements have a
`.text` attribute, even though its value is the empty-string for
element-types such as CheckBox and PageBreak which inherently have no
text. As a consequence, several `cast()` wrappers are no longer required
to satisfy strict type-checking.
This also allows a `CheckBox` element to be combined with `Text`
subtypes during chunking, essentially the same way `PageBreak` is,
contributing no text to the chunk.
Also, remove the `_NonTextSection` object which previously wrapped a
`CheckBox` element during pre-chunking as it is no longer required.
Closes#1985
**Summary.** Due to an interaction of coding errors, HTML text in
`TableChunk` splits of a `Table` element were repeating the entire HTML
for the table in each chunk.
**Technical Summary.** This behavior was fixed but not published in the
last chunking PR of a series. Finish up that PR and submit it all here.
This PR extracts chunking to the particular Section type (each has their
own distinct chunking behavior).
### Executive Summary
The structure of element metadata is currently static, meaning only
predefined fields can appear in the metadata. We would like the
flexibility for end-users, at their own discretion, to define and use
additional metadata fields that make sense for their particular
use-case.
### Concepts
A key concept for dynamic metadata is _known field_. A known-field is
one of those explicitly defined on `ElementMetadata`. Each of these has
a type and can be specified when _constructing_ a new `ElementMetadata`
instance. This is in contrast to an _end-user defined_ (or _ad-hoc_)
metadata field, one not known at "compile" time and added at the
discretion of an end-user to suit the purposes of their application.
An ad-hoc field can only be added by _assignment_ on an already
constructed instance.
### End-user ad-hoc metadata field behaviors
An ad-hoc field can be added to an `ElementMetadata` instance by
assignment:
```python
>>> metadata = ElementMetadata()
>>> metadata.coefficient = 0.536
```
A field added in this way can be accessed by name:
```python
>>> metadata.coefficient
0.536
```
and that field will appear in the JSON/dict for that instance:
```python
>>> metadata = ElementMetadata()
>>> metadata.coefficient = 0.536
>>> metadata.to_dict()
{"coefficient": 0.536}
```
However, accessing a "user-defined" value that has _not_ been assigned
on that instance raises `AttributeError`:
```python
>>> metadata.coeffcient # -- misspelled "coefficient" --
AttributeError: 'ElementMetadata' object has no attribute 'coeffcient'
```
This makes "tagging" a metadata item with a value very convenient, but
entails the proviso that if an end-user wants to add a metadata field to
_some_ elements and not others (sparse population), AND they want to
access that field by name on ANY element and receive `None` where it has
not been assigned, they will need to use an expression like this:
```python
coefficient = metadata.coefficient if hasattr(metadata, "coefficient") else None
```
### Implementation Notes
- **ad-hoc metadata fields** are discarded during consolidation (for
chunking) because we don't have a consolidation strategy defined for
those. We could consider using a default consolidation strategy like
`FIRST` or possibly allow a user to register a strategy (although that
gets hairy in non-private and multiple-memory-space situations.)
- ad-hoc metadata fields **cannot start with an underscore**.
- We have no way to distinguish an ad-hoc field from any "noise" fields
that might appear in a JSON/dict loaded using `.from_dict()`, so unlike
the original (which only loaded known-fields), we'll rehydrate anything
that we find there.
- No real type-safety is possible on ad-hoc fields but the type-checker
does not complain because the type of all ad-hoc fields is `Any` (which
is the best available behavior in my view).
- We may want to consider whether end-users should be able to add ad-hoc
fields to "sub" metadata objects too, like `DataSourceMetadata` and
conceivably `CoordinatesMetadata` (although I'm not immediately seeing a
use-case for the second one).
**Executive Summary.** When the elements in a _section_ are combined
into a _chunk_, the metadata in each of the elements is _consolidated_
into a single `ElementMetadata` instance. There are two main problems
with the current implementation:
1. The current algorithm simply uses the metadata of the first element
as the metadata for the chunk. This produces:
- **empty chunk metadata** when the first element has no metadata, such
as a `PageBreak("")`
- **missing chunk metadata** when the first element contains only
partial metadata such as a `Header()` or `Footer()`
- **misleading metadata** when the first element contains values
applicable only to that element, such as `category_depth`, `coordinates`
(bounding-box), `header_footer_type`, or `parent_id`
2. Second, list metadata such as `emphasized_text_content`,
`emphasized_text_tags`, `link_texts` and `link_urls` is only combined
when it is unique within the combined list. These lists are "unzipped"
pairs. For example, the first `link_texts` corresponds to the first
`link_urls` value. When an item is removed from one (because it matches
a prior entry) and not the other (say same text "here" but different
URL) the positional correspondence is broken and downstream processing
will at best be wrong, at worst raise an exception.
### Technical Discussion
Element metadata cannot be determined in the general case simply by
sampling that of the first element. At the same time, a simple union of
all values is also not sufficient. To effectively consolidate the
current variety of metadata fields we need four distinct strategies,
selecting which to apply to each field based on that fields provenance
and other characteristics.
The four strategies are:
- `FIRST` - Select the first non-`None` value across all the elements.
Several fields are determined by the document source (`filename`,
`file_directory`, etc.) and will not change within the output of a
single partitioning run. They might not appear in every element, but
they will be the same whenever they do appear. This strategy takes the
first one that appears, if any, as proxy for the value for the entire
chunk.
- `LIST` - Consolidate the four list fields like
`emphasized_text_content` and `link_urls` by concatenating them in
element order (no set semantics apply). All values from `elements[n]`
appear before those from `elements[n+1]` and existing order is
preserved.
- `LIST_UNIQUE` - Combine only unique elements across the (list) values
of the elements, preserving order in which a unique item first appeared.
- `REGEX` - Regex metadata has its own rules, including adjusting the
`start` and `end` offset of each match based its new position in the
concatenated text.
- `DROP` - Not all metadata can or should appear in a chunk. For
example, a chunk cannot be guaranteed to have a single `category_depth`
or `parent_id`.
Other strategies such as `COORDINATES` could be added to consolidate the
bounding box of the chunk from the coordinates of its elements, roughly
`min(lefts)`, `max(rights)`, etc. Others could be `LAST`, `MAJORITY`, or
`SUM` depending on how metadata evolves.
The proposed strategy assignments are these:
- `attached_to_filename`: FIRST,
- `category_depth`: DROP,
- `coordinates`: DROP,
- `data_source`: FIRST,
- `detection_class_prob`: DROP, # -- ? confirm --
- `detection_origin`: DROP, # -- ? confirm --
- `emphasized_text_contents`: LIST,
- `emphasized_text_tags`: LIST,
- `file_directory`: FIRST,
- `filename`: FIRST,
- `filetype`: FIRST,
- `header_footer_type`: DROP,
- `image_path`: DROP,
- `is_continuation`: DROP, # -- not expected, added by chunking, not
before --
- `languages`: LIST_UNIQUE,
- `last_modified`: FIRST,
- `link_texts`: LIST,
- `link_urls`: LIST,
- `links`: DROP, # -- deprecated field --
- `max_characters`: DROP, # -- unused in code, probably remove from
ElementMetadata --
- `page_name`: FIRST,
- `page_number`: FIRST,
- `parent_id`: DROP,
- `regex_metadata`: REGEX,
- `section`: FIRST, # -- section unconditionally breaks on new section
--
- `sent_from`: FIRST,
- `sent_to`: FIRST,
- `subject`: FIRST,
- `text_as_html`: DROP, # -- not expected, only occurs in TableSection
--
- `url`: FIRST,
**Assumptions:**
- each .eml file is partitioned->chunked separately (not in batches),
therefore
sent-from, sent-to, and subject will not change within a section.
### Implementation
Implementation of this behavior requires two steps:
1. **Collect** all non-`None` values from all elements, each in a
sequence by field-name. Fields not populated in any of the elements do
not appear in the collection.
```python
all_meta = {
"filename": ["memo.docx", "memo.docx"]
"link_texts": [["here", "here"], ["and here"]]
"parent_id": ["f273a7cb", "808b4ced"]
}
```
2. **Apply** the specified strategy to each item in the overall
collection to produce the consolidated chunk meta (see implementation).
### Factoring
For the following reasons, the implementation of metadata consolidation
is extracted from its current location in `chunk_by_title()` to a
handful of collaborating methods in `_TextSection`.
- The current implementation of metadata consolidation "inline" in
`chunk_by_title()` already has too many moving pieces to be understood
without extended study. Adding strategies to that would make it worse.
- `_TextSection` is the only section type where metadata is consolidated
(the other two types always have exactly one element so already exactly
one metadata.)
- `_TextSection` is already the expert on all the information required
to consolidate metadata, in particular the elements that make up the
section and their text.
Some other problems were also fixed in that transition, such as mutation
of elements during the consolidation process.
### Technical Risk: adding new `ElementMetadata` field breaks metadata
If each metadata field requires a strategy assignment to be consolidated
and a developer adds a new `ElementMetadata` field without adding a
corresponding strategy mapping, metadata consolidation could break or
produce incorrect results.
This risk can be mitigated multiple ways:
1. Add a test that verifies a strategy is defined for each
(Recommended).
2. Define a default strategy, either `DROP` or `FIRST` for scalar types,
`LIST` for list types.
3. Raise an exception when an unknown metadata field is encountered.
This PR implements option 1 such that a developer will be notified
before merge if they add a new metadata field but do not define a
strategy for it.
### Other Considerations
- If end-users can in-future add arbitrary metadata fields _before_
chunking, then we'll need to define metadata-consolidation behavior for
such fields. Depending on how we implement user-defined metadata fields
we might:
- Require explicit definition of a new metadata field before use,
perhaps with a method like `ElementMetadata.add_custom_field()` which
requires a consolidation strategy to be defined (and/or has a default
value).
- Have a default strategy, perhaps `DROP` or `FIRST`, or `LIST` if the
field is type `list`.
### Further Context
Metadata is only consolidated for `TextSection` because the other two
section types (`TableSection` and `NonTextSection`) can only contain a
single element.
---
## Further discussion on consolidation strategy by field
### document-static
These fields are very likely to be the same for all elements in a single
document:
- `attached_to_filename`
- `data_source`
- `file_directory`
- `filename`
- `filetype`
- `last_modified`
- `sent_from`
- `sent_to`
- `subject`
- `url`
*Consolidation strategy:* `FIRST` - use first one found, if any.
### section-static
These fields are very likely to be the same for all elements in a single
section, which is the scope we really care about for metadata
consolidation:
- `section` - an EPUB document-section unconditionally starts new
section.
*Consolidation strategy:* `FIRST` - use first one found, if any.
### consolidated list-items
These `List` fields are consolidated by concatenating the lists from
each element that has one:
- `emphasized_text_contents`
- `emphasized_text_tags`
- `link_texts`
- `link_urls`
- `regex_metadata` - special case, this one gets indexes adjusted too.
*Consolidation strategy:* `LIST` - concatenate lists across elements.
### dynamic
These fields are likely to hold unique data for each element:
- `category_depth`
- `coordinates`
- `image_path`
- `parent_id`
*Consolidation strategy:*
- `DROP` as likely misleading.
- `COORDINATES` strategy could be added to compute the bounding box from
all bounding boxes.
- Consider allowing if they are all the same, perhaps an `ALL` strategy.
### slow-changing
These fields are somewhere in-between, likely to be common between
multiple elements but varied within a document:
- `header_footer_type` - *strategy:* drop as not-consolidatable
- `languages` - *strategy:* take first occurence
- `page_name` - *strategy:* take first occurence
- `page_number` - *strategy:* take first occurence, will all be the same
when `multipage_sections` is `False`. Worst-case semantics are "this
chunk began on this page".
### N/A
These field types do not figure in metadata-consolidation:
- `detection_class_prob` - I'm thinking this is for debug and should not
appear in chunks, but need confirmation.
- `detection_origin` - for debug only
- `is_continuation` - is _produced_ by chunking, never by partitioning
(not in our code anyway).
- `links` (deprecated, probably should be dropped)
- `max_characters` - is unused as far as I can tell, is unreferenced in
source code. Should be removed from `ElementMetadata` as far as I can
tell.
- `text_as_html` - only appears in a `Table` element, each of which
appears in its own section so needs no consolidation. Never appears in
`TextSection`.
*Consolidation strategy:* `DROP` any that appear (several never will)
This PR introduces `clean_pdfminer_inner_elements` , which deletes
pdfminer elements inside other detection origins such as YoloX or
detectron.
This function returns the clean document.
Also, the ingest-test fixtures were updated to reflect the new standard
output.
The best way to check that this function is working properly is check
the new test `test_clean_pdfminer_inner_elements` in
`test_unstructured/partition/utils/test_processing_elements.py`
---------
Co-authored-by: Roman Isecke <roman@unstructured.io>
Co-authored-by: ryannikolaidis <1208590+ryannikolaidis@users.noreply.github.com>
Co-authored-by: rbiseck3 <rbiseck3@users.noreply.github.com>
Co-authored-by: Roman Isecke <136338424+rbiseck3@users.noreply.github.com>
### disassociated-titles
**Executive Summary**. Section titles are often combined with the prior
section and then missing from the section they belong to.
_Chunk combination_ is a behavior in which two succesive small chunks
are combined into a single chunk that better fills the chunk window.
Chunking can be and by default is configured to combine sequential small
chunks that will together fit within the full chunk window (default 500
chars).
Combination is only valid for "whole" chunks. The current implementation
attempts to combine at the element level (in the sectioner), meaning a
small initial element (such as a `Title`) is combined with the prior
section without considering the remaining length of the section that
title belongs to. This frequently causes a title element to be removed
from the chunk it belongs to and added to the prior, otherwise
unrelated, chunk.
Example:
```python
elements: List[Element] = [
Title("Lorem Ipsum"), # 11
Text("Lorem ipsum dolor sit amet consectetur adipiscing elit."), # 55
Title("Rhoncus"), # 7
Text("In rhoncus ipsum sed lectus porta volutpat. Ut fermentum."), # 57
]
chunks = chunk_by_title(elements, max_characters=80, combine_text_under_n_chars=80)
# -- want --------------------
CompositeElement('Lorem Ipsum\n\nLorem ipsum dolor sit amet consectetur adipiscing elit.')
CompositeElement('Rhoncus\n\nIn rhoncus ipsum sed lectus porta volutpat. Ut fermentum.')
# -- got ---------------------
CompositeElement('Lorem Ipsum\n\nLorem ipsum dolor sit amet consectetur adipiscing elit.\n\nRhoncus')
CompositeElement('In rhoncus ipsum sed lectus porta volutpat. Ut fermentum.')
```
**Technical Summary.** Combination cannot be effectively performed at
the element level, at least not without complicating things with
arbitrary look-ahead into future elements. Much more straightforward is
to combine sections once they have been formed from the element stream.
**Fix.** Introduce an intermediate stream processor that accepts a
stream of sections and emits a stream of sometimes-combined sections.
The solution implemented in this PR builds upon introducing `_Section`
objects to replace the `List[Element]` primitive used previously:
- `_TextSection` gets the `.combine()` method and `.text_length`
property which allows a combining client to produce a combined section
(only text-sections are ever combined).
- `_SectionCombiner` is introduced to encapsulate the logic of
combination, acting as a "filter", accepting a stream of sections and
emitting the same type, just with some resulting from two or more
combined input sections: `(Iterable[_Section]) -> Iterator[_Section]`.
- `_TextSectionAccumulator` is a helper to `_SectionCombiner` that takes
responsibility for repeatedly accumulating sections, characterizing
their length and doing the actual combining (calling
`_Section.combine(other_section)`) when instructed. Very similar in
concept to `_TextSectionBuilder`, just at the section level instead of
element level.
- Remove attempts to combine sections at the element level from
`_split_elements_by_title_and_table()` and install `_SectionCombiner` as
filter between sectioner and chunker.
### sectioner-does-not-consider-separator-length
**Executive Summary.** A primary responsibility of the sectioner is to
minimize the number of chunks that need to be split mid-text. It does
this by computing text-length of the section being formed and
"finishing" the section when adding another element would extend its
text beyond the window size.
When element-text is consolidated into a chunk, the text of each element
is joined, separated by a "blank-line" (`"\n\n"`). The sectioner does
not currently consider the added length of separators (2-chars each) and
so forms sections that need to be split mid-text when chunked.
Chunk-splitting should only be necessary when the text of a single
element is longer than the chunking window.
**Example**
```python
elements: List[Element] = [
Title("Chunking Priorities"), # 19 chars
ListItem("Divide text into manageable chunks"), # 34 chars
ListItem("Preserve semantic boundaries"), # 28 chars
ListItem("Minimize mid-text chunk-splitting"), # 33 chars
] # 114 chars total but 120 chars with separators
chunks = chunk_by_title(elements, max_characters=115)
```
Want:
```python
[
CompositeElement(
"Chunking Priorities"
"\n\nDivide text into manageable chunks"
"\n\nPreserve semantic boundaries"
),
CompositeElement("Minimize mid-text chunk-splitting"),
]
```
Got:
```python
[
CompositeElement(
"Chunking Priorities"
"\n\nDivide text into manageable chunks"
"\n\nPreserve semantic boundaries"
"\n\nMinimize mid-text chunk-spli"),
)
CompositeElement("tting")
```
### Technical Summary
Because the sectioner does not consider separator (`"\n\n"`) length when
it computes the space remaining in the section, it over-populates the
section and when the chunker concatenates the element text (each
separated by the separator) the text exceeds the window length and the
chunk must be split mid-text, even though there was an even element
boundary it could have been split on.
### Fix
Consider separator length in the space-remaining computation.
The solution here extracts both the `section.text_length` and
`section.space_remaining` computations to a `_TextSectionBuilder` object
which removes the need for the sectioner
(`_split_elements_by_title_and_table()`) to deal with primitives
(List[Element], running text length, separator length, etc.) and allows
it to focus on the rules of when to start a new section.
This solution may seem like overkill at the moment and indeed it would
be except it forms the foundation for adding section-level chunk
combination (fix: dissociated title elements) in the next PR. The
objects introduced here will gain several additional responsibilities in
the next few chunking PRs in the pipeline and will earn their place.
* **Removed `ebooklib` as a dependency** `ebooklib` is licensed under
AGPL3, which is incompatible with the Apache 2.0 license. Thus it is
being removed.
### `chunk_by_title()` interface is "rude"
**Executive Summary.** Perhaps the most commonly specified option for
`chunk_by_title()` is `max_characters` (default: 500), which specifies
the chunk window size.
When a user specifies this value, they get an error message:
```python
>>> chunks = chunk_by_title(elements, max_characters=100)
ValueError: Invalid values for combine_text_under_n_chars, new_after_n_chars, and/or max_characters.
```
A few of the things that might reasonably pass through a user's mind at
such a moment are:
* "Is `110` not a valid value for `max_characters`? Why would that be?"
* "I didn't specify a value for `combine_text_under_n_chars` or
`new_after_n_chars`, in fact I don't know what they are because I
haven't studied the documentation and would prefer not to; I just want
smaller chunks! How could I supply an invalid value when I haven't
supplied any value at all for these?"
* "Which of these values is the problem? Why are you making me figure
that out for myself? I'm sure the code knows which one is not valid, why
doesn't it share that information with me? I'm busy here!"
In this particular case, the problem is that
`combine_text_under_n_chars` (defaults to 500) is greater than
`max_characters`, which means it would never take effect (which is
actually not a problem in itself).
To fix this, once figuring out that was the problem, probably after
opening an issue and maybe reading the source code, the user would need
to specify:
```python
>>> chunks = chunk_by_title(
... elements, max_characters=100, combine_text_under_n_chars=100
... )
```
This and other stressful user scenarios can be remedied by:
* Using "active" defaults for the `combine_text_under_n_chars` and
`new_after_n_chars` options.
* Providing a specific error message for each way a constraint may be
violated, such that direction to remedy the problem is immediately clear
to the user.
An *active default* is for example:
* Make the default for `combine_text_under_n_chars: int | None = None`
such that the code can detect when it has not been specified.
* When not specified, set its value to `max_characters`, the same as its
current (static) default.
This particular change would avoid the behavior in the motivating
example above.
Another alternative for this argument is simply:
```python
combine_text_under_n_chars = min(max_characters, combine_text_under_n_chars)
```
### Fix
1. Add constraint-specific error messages.
2. Use "active" defaults for `combine_text_under_n_ chars` and
`new_after_n_chars`.
3. Improve docstring to describe active defaults, and explain other
argument behaviors, in particular identifying suppression options like
`combine_text_under_n_chars = 0` to disable chunk combining.
Carrying `skip_infer_table_types` to `infer_table_structure` in
partition flow. Now PPT/X, DOC/X, etc. Table elements should not have a
`text_as_html` field.
Note: I've continued to exclude this var from partitioners that go
through html flow, I think if we've already got the html it doesn't make
sense to carry the infer variable along, since we're not 'infer-ing' the
html table in these cases.
TODO:
✅ add unit tests
---------
Co-authored-by: ryannikolaidis <1208590+ryannikolaidis@users.noreply.github.com>
Co-authored-by: amanda103 <amanda103@users.noreply.github.com>
**Executive Summary.** Code inspection in preparation for adding the
chunk-overlap feature revealed a bug causing split-chunks to be inserted
out-of-order. For example, elements like this:
```
Text("One" + 400 chars)
Text("Two" + 400 chars)
Text("Three" + 600 chars)
Text("Four" + 400 chars)
Text("Five" + 600 chars)
```
Should produce chunks:
```
CompositeElement("One ...") # (400 chars)
CompositeElement("Two ...") # (400 chars)
CompositeElement("Three ...") # (500 chars)
CompositeElement("rest of Three ...") # (100 chars)
CompositeElement("Four") # (400 chars)
CompositeElement("Five ...") # (500 chars)
CompositeElement("rest of Five ...") # (100 chars)
```
but produced this instead:
```
CompositeElement("Five ...") # (500 chars)
CompositeElement("rest of Five ...") # (100 chars)
CompositeElement("Three ...") # (500 chars)
CompositeElement("rest of Three ...") # (100 chars)
CompositeElement("One ...") # (400 chars)
CompositeElement("Two ...") # (400 chars)
CompositeElement("Four") # (400 chars)
```
This PR fixes that behavior that was introduced on Oct 9 this year in
commit: f98d5e65 when adding chunk splitting.
**Technical Summary**
The essential transformation of chunking is:
```
elements sections chunks
List[Element] -> List[List[Element]] -> List[CompositeElement]
```
1. The _sectioner_ (`_split_elements_by_title_and_table()`) _groups_
semantically-related elements into _sections_ (`List[Element]`), in the
best case, that would be a title (heading) and the text that follows it
(until the next title). A heading and its text is often referred to as a
_section_ in publishing parlance, hence the name.
2. The _chunker_ (`chunk_by_title()` currently) does two things:
1. first it _consolidates_ the elements of each section into a single
`ConsolidatedElement` object (a "chunk"). This includes both joining the
element text into a single string as well as consolidating the metadata
of the section elements.
2. then if necessary it _splits_ the chunk into two or more
`ConsolidatedElement` objects when the consolidated text is too long to
fit in the specified window (`max_characters`).
Chunk splitting is only required when a single element (like a big
paragraph) has text longer than the specified window. Otherwise a
section and the chunk that derives from it reflects an even element
boundary.
`chunk_by_title()` was elaborated in commit f98d5e65 to add this
"chunk-splitting" behavior.
At the time there was some notion of wanting to "split from the end
backward" such that any small remainder chunk would appear first, and
could possibly be combined with a small prior chunk. To accomplish this,
split chunks were _inserted_ at the beginning of the list instead of
_appended_ to the end.
The `chunked_elements` variable (`List[CompositeElement]`) holds the
sequence of chunks that result from the chunking operation and is the
returned value for `chunk_by_title()`. This was the list
"split-from-the-end" chunks were inserted at the beginning of and that
unfortunately produces this out-of-order behavior because the insertion
was at the beginning of this "all-chunks-in-document" list, not a
sublist just for this chunk.
Further, the "split-from-the-end" behavior can produce no benefit
because chunks are never combined, only _elements_ are combined (across
semantic boundaries into a single section when a section is small) and
sectioning occurs _prior_ to chunking.
The fix is to rework the chunk-splitting passage to a straighforward
iterative algorithm that works both when a chunk must be split and when
it doesn't. This algorithm is also very easily extended to implement
split-chunk-overlap which is coming up in an immediately following PR.
```python
# -- split chunk into CompositeElements objects maxlen or smaller --
text_len = len(text)
start = 0
remaining = text_len
while remaining > 0:
end = min(start + max_characters, text_len)
chunked_elements.append(CompositeElement(text=text[start:end], metadata=chunk_meta))
start = end - overlap
remaining = text_len - end
```
*Forensic analysis*
The out-of-order-chunks behavior was introduced in commit 4ea71683 on
10/09/2023 in the same PR in which chunk-splitting was introduced.
---------
Co-authored-by: Shreya Nidadavolu <shreyanid9@gmail.com>
Co-authored-by: shreyanid <42684285+shreyanid@users.noreply.github.com>
**Executive Summary.** Introducing strict type-checking as preparation
for adding the chunk-overlap feature revealed a type mismatch for
regex-metadata between chunking tests and the (authoritative)
ElementMetadata definition. The implementation of regex-metadata aspects
of chunking passed the tests but did not produce the appropriate
behaviors in production where the actual data-structure was different.
This PR fixes these two bugs.
1. **Over-chunking.** The presence of `regex-metadata` in an element was
incorrectly being interpreted as a semantic boundary, leading to such
elements being isolated in their own chunks.
2. **Discarded regex-metadata.** regex-metadata present on the second or
later elements in a section (chunk) was discarded.
**Technical Summary**
The type of `ElementMetadata.regex_metadata` is `Dict[str,
List[RegexMetadata]]`. `RegexMetadata` is a `TypedDict` like `{"text":
"this matched", "start": 7, "end": 19}`.
Multiple regexes can be specified, each with a name like "mail-stop",
"version", etc. Each of those may produce its own set of matches, like:
```python
>>> element.regex_metadata
{
"mail-stop": [{"text": "MS-107", "start": 18, "end": 24}],
"version": [
{"text": "current: v1.7.2", "start": 7, "end": 21},
{"text": "supersedes: v1.7.0", "start": 22, "end": 40},
],
}
```
*Forensic analysis*
* The regex-metadata feature was added by Matt Robinson on 06/16/2023
commit: 4ea71683. The regex_metadata data structure is the same as when
it was added.
* The chunk-by-title feature was added by Matt Robinson on 08/29/2023
commit: f6a745a7. The mistaken regex-metadata data structure in the
tests is present in that commit.
Looks to me like a mis-remembering of the regex-metadata data-structure
and insufficient type-checking rigor (type-checker strictness level set
too low) to warn of the mistake.
**Over-chunking Behavior**
The over-chunking looked like this:
Chunking three elements with regex metadata should combine them into a
single chunk (`CompositeElement` object), subject to maximum size rules
(default 500 chars).
```python
elements: List[Element] = [
Title(
"Lorem Ipsum",
metadata=ElementMetadata(
regex_metadata={"ipsum": [RegexMetadata(text="Ipsum", start=6, end=11)]}
),
),
Text(
"Lorem ipsum dolor sit amet consectetur adipiscing elit.",
metadata=ElementMetadata(
regex_metadata={"dolor": [RegexMetadata(text="dolor", start=12, end=17)]}
),
),
Text(
"In rhoncus ipsum sed lectus porta volutpat.",
metadata=ElementMetadata(
regex_metadata={"ipsum": [RegexMetadata(text="ipsum", start=11, end=16)]}
),
),
]
chunks = chunk_by_title(elements)
assert chunks == [
CompositeElement(
"Lorem Ipsum\n\nLorem ipsum dolor sit amet consectetur adipiscing elit.\n\nIn rhoncus"
" ipsum sed lectus porta volutpat."
)
]
```
Observed behavior looked like this:
```python
chunks => [
CompositeElement('Lorem Ipsum')
CompositeElement('Lorem ipsum dolor sit amet consectetur adipiscing elit.')
CompositeElement('In rhoncus ipsum sed lectus porta volutpat.')
]
```
The fix changed the approach from breaking on any metadata field not in
a specified group (`regex_metadata` was missing from this group) to only
breaking on specified fields (whitelisting instead of blacklisting).
This avoids overchunking every time we add a new metadata field and is
also simpler and easier to understand. This change in approach is
discussed in more detail here #1790.
**Dropping regex-metadata Behavior**
Chunking this section:
```python
elements: List[Element] = [
Title(
"Lorem Ipsum",
metadata=ElementMetadata(
regex_metadata={"ipsum": [RegexMetadata(text="Ipsum", start=6, end=11)]}
),
),
Text(
"Lorem ipsum dolor sit amet consectetur adipiscing elit.",
metadata=ElementMetadata(
regex_metadata={
"dolor": [RegexMetadata(text="dolor", start=12, end=17)],
"ipsum": [RegexMetadata(text="ipsum", start=6, end=11)],
}
),
),
Text(
"In rhoncus ipsum sed lectus porta volutpat.",
metadata=ElementMetadata(
regex_metadata={"ipsum": [RegexMetadata(text="ipsum", start=11, end=16)]}
),
),
]
```
..should produce this regex_metadata on the single produced chunk:
```python
assert chunk == CompositeElement(
"Lorem Ipsum\n\nLorem ipsum dolor sit amet consectetur adipiscing elit.\n\nIn rhoncus"
" ipsum sed lectus porta volutpat."
)
assert chunk.metadata.regex_metadata == {
"dolor": [RegexMetadata(text="dolor", start=25, end=30)],
"ipsum": [
RegexMetadata(text="Ipsum", start=6, end=11),
RegexMetadata(text="ipsum", start=19, end=24),
RegexMetadata(text="ipsum", start=81, end=86),
],
}
```
but instead produced this:
```python
regex_metadata == {"ipsum": [{"text": "Ipsum", "start": 6, "end": 11}]}
```
Which is the regex-metadata from the first element only.
The fix was to remove the consolidation+adjustment process from inside
the "list-attribute-processing" loop (because regex-metadata is not a
list) and process regex metadata separately.
This PR adds the `max_characters` (hard max) param to non-table element
chunking. Additionally updates the `num_characters` metadata to
`max_characters` to make it clearer which param we're referencing.
To test:
```
from unstructured.partition.html import partition_html
filename = "example-docs/example-10k-1p.html"
chunk_elements = partition_html(
filename,
chunking_strategy="by_title",
combine_text_under_n_chars=0,
new_after_n_chars=50,
max_characters=100,
)
for chunk in chunk_elements:
print(len(chunk.text))
# previously we were only respecting the "soft max" (default of 500) for elements other than tables
# now we should see that all the elements have text fields under 100 chars.
```
---------
Co-authored-by: cragwolfe <crag@unstructured.io>
This change is adding to our `add_chunking_strategy` logic so that we
are able to chunk Table elements' `text` and `text_as_html` params. In
order to keep the functionality under the same `by_title` chunking
strategy we have renamed the `combine_under_n_chars` to
`max_characters`. It functions the same way for the combining elements
under Title's, as well as specifying a chunk size (in chars) for
TableChunk elements.
*renaming the variable to `max_characters` will also reflect the 'hard
max' we will implement for large elements in followup PRs
Additionally -> some lint changes snuck in when I ran `make tidy` hence
the minor changes in unrelated files :)
TODO:
✅ add unit tests
--> note: added where I could to unit tests! Some unit tests I just
clarified that the chunking strategy was now 'by_title' because we don't
have a file example that has Table elements to test the
'by_num_characters' chunking strategy
✅ update changelog
To manually test:
```
In [1]: filename="example-docs/example-10k.html"
In [2]: from unstructured.chunking.title import chunk_table_element
In [3]: from unstructured.partition.auto import partition
In [4]: elements = partition(filename)
# element at -2 happens to be a Table, and we'll get chunks of char size 4 here
In [5]: chunks = chunk_table_element(elements[-2], 4)
# examine text and text_as_html params
ln [6]: for c in chunks:
print(c.text)
print(c.metadata.text_as_html)
```
---------
Co-authored-by: Yao You <theyaoyou@gmail.com>
### Summary
Partial solution to #1185.
Related to #1222.
Creates decorator from `chunk_by_title` cleaning brick.
Breaks a document into sections based on the presence of Title elements.
Also starts a new section under the following conditions:
- If metadata changes, indicating a change in section or page or a
switch to processing attachments. If `multipage_sections=True`, sections
can span pages. `multipage_sections` defaults to True.
- If the length of the section exceeds `new_after_n_chars` characters.
The default is 1500. The **chunking function does not split individual
elements**, so it's possible for a section to exceed that threshold if
an individual element if over `new_after_n_chars characters`, which
could occur with a long NarrativeText element.
Combines sections under these conditions
- Sections under `combine_under_n_chars` characters are combined. The
default is 500.
### Testing
from unstructured.partition.html import partition_html
url = "https://understandingwar.org/backgrounder/russian-offensive-campaign-assessment-august-27-2023-0"
chunks = partition_html(url=url, chunking_strategy="by_title")
for chunk in chunks:
print(chunk)
print("\n\n" + "-"*80)
input()
### Summary
An initial pass on smart chunking for RAG applications. Breaks a
document into sections based on the presence of `Title` elements. Also
starts a new section under the following conditions:
- If metadata changes, indicating a change in section or page or a
switch to processing attachments. If `multipage_sections=True`, sections
can span pages. `multipage_sections` defaults to True.
- If the length of the section exceeds `new_after_n_chars` characters.
The default is `1500`. The chunking function does not split individual
elements, so it's possible for a section to exceed that threshold if an
individual element if over `new_after_n_chars` characters, which could
occur with a long `NarrativeText` element.
- Section under `combine_under_n_chars` characters are combined. The
default is `500`.
### Testing
```python
from unstructured.partition.html import partition_html
from unstructured.chunking.title import chunk_by_title
url = "https://understandingwar.org/backgrounder/russian-offensive-campaign-assessment-august-27-2023-0"
elements = partition_html(url=url)
chunks = chunk_by_title(elements)
for chunk in chunks:
print(chunk)
print("\n\n" + "-"*80)
input()
```
