| |
| |
| |
|
|
| from typing import Dict, List, Optional |
|
|
| from haystack import component, logging |
| from haystack.lazy_imports import LazyImport |
|
|
| logger = logging.getLogger(__name__) |
|
|
| with LazyImport("Run 'pip install langdetect'") as langdetect_import: |
| import langdetect |
|
|
|
|
| @component |
| class TextLanguageRouter: |
| """ |
| Routes text strings to different output connections based on their language. |
| |
| Provide a list of languages during initialization. If the document's text doesn't match any of the |
| specified languages, the metadata value is set to "unmatched". |
| For routing documents based on their language, use the DocumentLanguageClassifier component, |
| followed by the MetaDataRouter. |
| |
| ### Usage example |
| |
| ```python |
| from haystack import Pipeline, Document |
| from haystack.components.routers import TextLanguageRouter |
| from haystack.document_stores.in_memory import InMemoryDocumentStore |
| from haystack.components.retrievers.in_memory import InMemoryBM25Retriever |
| |
| document_store = InMemoryDocumentStore() |
| document_store.write_documents([Document(content="Elvis Presley was an American singer and actor.")]) |
| |
| p = Pipeline() |
| p.add_component(instance=TextLanguageRouter(languages=["en"]), name="text_language_router") |
| p.add_component(instance=InMemoryBM25Retriever(document_store=document_store), name="retriever") |
| p.connect("text_language_router.en", "retriever.query") |
| |
| result = p.run({"text_language_router": {"text": "Who was Elvis Presley?"}}) |
| assert result["retriever"]["documents"][0].content == "Elvis Presley was an American singer and actor." |
| |
| result = p.run({"text_language_router": {"text": "ένα ελληνικό κείμενο"}}) |
| assert result["text_language_router"]["unmatched"] == "ένα ελληνικό κείμενο" |
| ``` |
| """ |
|
|
| def __init__(self, languages: Optional[List[str]] = None): |
| """ |
| Initialize the TextLanguageRouter component. |
| |
| :param languages: A list of ISO language codes. |
| See the supported languages in [`langdetect` documentation](https://github.com/Mimino666/langdetect#languages). |
| If not specified, defaults to ["en"]. |
| """ |
| langdetect_import.check() |
| if not languages: |
| languages = ["en"] |
| self.languages = languages |
| component.set_output_types(self, unmatched=str, **{language: str for language in languages}) |
|
|
| def run(self, text: str) -> Dict[str, str]: |
| """ |
| Routes the text strings to different output connections based on their language. |
| |
| If the document's text doesn't match any of the specified languages, the metadata value is set to "unmatched". |
| |
| :param text: A text string to route. |
| |
| :returns: A dictionary in which the key is the language (or `"unmatched"`), |
| and the value is the text. |
| |
| :raises TypeError: If the input is not a string. |
| """ |
| if not isinstance(text, str): |
| msg = ( |
| "TextLanguageRouter expects a string as input. In case you want to classify a document, please use " |
| "the DocumentLanguageClassifier and MetaDataRouter." |
| ) |
| raise TypeError(msg) |
|
|
| output: Dict[str, str] = {} |
|
|
| detected_language = self._detect_language(text) |
| if detected_language in self.languages: |
| output[detected_language] = text |
| else: |
| output["unmatched"] = text |
|
|
| return output |
|
|
| def _detect_language(self, text: str) -> Optional[str]: |
| try: |
| language = langdetect.detect(text) |
| except langdetect.LangDetectException as exception: |
| logger.warning("Langdetect cannot detect the language of text. Error: {error}", error=exception) |
| |
| logger.debug("Langdetect cannot detect the language of text: {text}", text=text) |
| language = None |
| return language |
|
|
