[LLM pipeline] Language filter component (#232)

This PR adds the first component for the LLM dataset creation pipeline.
The component is a language filter which filters out rows in a provided
dataframe that are not matching the provided language.
FastText is used for the language detection. 

Changes
- add component
- add unit test to test the filter logic inside of the component

Note: Did not create a pipeline that uses this component yet.

---------

Co-authored-by: NielsRogge <48327001+NielsRogge@users.noreply.github.com>
Co-authored-by: Robbe Sneyders <robbe.sneyders@gmail.com>

components/language_filter/Dockerfile

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+FROM --platform=linux/amd64 python:3.8-slim
+
+## System dependencies
+RUN apt-get update && \
+    apt-get upgrade -y && \
+    apt-get install git -y
+
+# install requirements
+COPY requirements.txt /
+RUN pip3 install --no-cache-dir -r requirements.txt
+
+# Set the working directory to the component folder
+WORKDIR /component/src
+
+# Copy over src-files
+COPY src/ .
+
+ENTRYPOINT ["python", "main.py"]

components/language_filter/README.md

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+# Language filter
+
+## Description
+This component is based on the `TransformComponent` and is used to filter a dataframe based on language. 
+It allows you to remove rows that do not match the provided language, thus providing a way to focus 
+on specific languages within your data.
+

components/language_filter/fondant_component.yaml

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+name: Filter languages
+description: A component that filters text based on the language.
+image: ghcr.io/ml6team/filter_language:latest
+
+consumes:
+  text:
+    fields:
+      data:
+        type: string
+
+args:
+  language:
+    description: A valid language code or identifier (e.g., "en", "fr", "de").
+    type: str

components/language_filter/requirements.txt

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+git+https://github.com/ml6team/fondant@main
+pyarrow>=7.0
+gcsfs==2023.4.00
+fasttext-wheel==0.9.2

components/language_filter/src/main.py

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+"""A component that filters text based on the language."""
+import logging
+
+import fasttext
+import pandas as pd
+
+from fondant.component import PandasTransformComponent
+
+logger = logging.getLogger(__name__)
+
+
+class LanguageIdentification:
+    """A class for language detection using FastText."""
+
+    def __init__(self, language, model_path: str = "lid.176.ftz"):
+        """
+        Initializes the LanguageDetect class.
+
+        Args:
+           language (str): language to filter on
+           model_path (str): The path to the FastText language identification model.
+        """
+        pretrained_lang_model_weight_path = model_path
+        self.language = language
+        self.model = fasttext.load_model(pretrained_lang_model_weight_path)
+
+    def predict_lang(self, text: str):
+        """
+        Detects the language of a text sequence.
+
+        Args:
+            text (str): The text for language detection.
+
+        Returns:
+            str: The predicted language label.
+        """
+        predictions = self.model.predict(text, k=1)
+        return predictions[0][0]
+
+    def is_language(self, row):
+        """Predict if text of a row is written in the defined language."""
+        return self.language in self.predict_lang(row["text"])
+
+
+class LanguageFilterComponent(PandasTransformComponent):
+    """Component that filter columns based on provided language."""
+
+    def setup(self, *, language):
+        """Setup language filter component.
+
+        Args:
+            language: Only keep text passages which are in the provided language.
+        """
+        self.lang_detector = LanguageIdentification(language)
+
+
+    def transform(self, dataframe: pd.DataFrame) -> pd.DataFrame:
+        """
+        Args:
+            dataframe: Pandas dataframe.
+
+        Returns:
+            Pandas dataframe
+        """
+        mask = dataframe.apply(self.lang_detector.is_language, axis=1)
+
+        return dataframe[mask]
+
+
+if __name__ == "__main__":
+    component = LanguageFilterComponent.from_args()
+    component.run()

components/language_filter/tests/language_filter_component_test.py

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+"""Unit test for language filter component."""
+import pandas as pd
+
+from components.language_filter.src.main import LanguageFilterComponent
+from fondant.component_spec import ComponentSpec
+
+
+def test_run_component_test():
+    """Test language filter component."""
+    # Given: Dataframe with text in different languages
+    data = [{"text": "Das hier ist ein Satz in deutscher Sprache"},
+            {"text": "This is a sentence in English"},
+            {"text": "Dit is een zin in het Nederlands"}]
+    dataframe = pd.DataFrame(data)
+
+    # When: The language filter component proceed the dataframe
+    # and filter out all entries which are not written in german
+    spec = ComponentSpec.from_file("../fondant_component.yaml")
+
+    component = LanguageFilterComponent(spec, input_manifest_path="./dummy_input_manifest.json",
+                                        output_manifest_path="./dummy_input_manifest.json",
+                                        metadata={},
+                                        user_arguments={"language": "de"},
+                                        )
+    component.setup(language="de")
+    dataframe = component.transform(dataframe=dataframe)
+
+    # Then: dataframe only contains one german row
+    assert len(dataframe) == 1
+    assert dataframe.loc[0]["text"] == "Das hier ist ein Satz in deutscher Sprache"
+
+
+def test_run_component_test_filter_out_all():
+    """Test language filter component."""
+    # Given: Dataframe with text in different languages
+    data = [{"text": "Das hier ist ein Satz in deutscher Sprache"},
+            {"text": "This is a sentence in English"},
+            {"text": "Dit is een zin in het Nederlands"}]
+    dataframe = pd.DataFrame(data)
+
+    # When: The language filter component proceed the dataframe
+    # and filter out all entries which are not written in french
+    spec = ComponentSpec.from_file("../fondant_component.yaml")
+
+    component = LanguageFilterComponent(spec, input_manifest_path="./dummy_input_manifest.json",
+                                        output_manifest_path="./dummy_input_manifest.json",
+                                        metadata={},
+                                        user_arguments={"language": "fr"},
+                                        )
+    component.setup()
+    dataframe = component.transform(dataframe=dataframe)
+
+    # Then: dataframe should contain no rows anymore
+    assert len(dataframe) == 0