LASER: xSIM++

This README shows how to calculate the xSIM++ error rate for a given language pair.

xSIM++ is an extension of xSIM. In comparison to xSIM, this evaluates using target-side data with additional synthetic, hard-to-distinguish examples. You can find more details about it in the publication: xSIM++: An Improved Proxy to Bitext Mining Performance for Low-Resource Languages.

Example usage

Simply run the example script bash ./eval.sh to download a sample dataset (flores200), download synthetically augmented English evaluation data from Flores, a sample encoder (laser2), and calculate both the sentence embeddings and the xSIM++ error rate for a set of (comma separated) languages.

The evaluation command is similar to xSIM, however there is an additional option to provide the comma-separated list of augmented languages: --tgt-aug-langs. These refer to languages in the chosen evaluation set which also have a separate augmented data file. In addition to the error rate, the script also provides a breakdown of the number of errors by type (e.g. incorrect entity/number etc.).

You can also calculate xsim++ for encoders hosted on HuggingFace sentence-transformers. For example, to use LaBSE you can modify/add the following arguments in the sample script:

--src-encoder LaBSE
--use-hugging-face
--embedding-dimension 768

Note: for HuggingFace encoders there is no need to specify --src-spm-model.