• Free software: Apache Software License 2.0
• Documentation: https://melusine.readthedocs.io.

Melusine is a high-level Python library for email classification and feature extraction, written in Python and capable of running on top of Scikit-Learn, Keras or Tensorflow. It is developed with a focus on emails written in french.

Use Melusine if you need a library which :

• Supports both convolutional networks and recurrent networks, as well as combinations of the two.
• Runs seamlessly on CPU and GPU.

Melusine is compatible with Python >= 3.5.

This package is designed for the preprocessing, classification and automatic summarization of emails written in french.

3 main subpackages are offered :

• prepare_email : to preprocess and clean emails.
• summarizer : to extract keywords from an email.
• models : to classify e-mails according to categories pre-defined by the user.

2 other subpackages are offered as building blocks :

• nlp_tools : to provide classic NLP tools such as tokenizer, phraser and embeddings.
• utils : to provide a TransformerScheduler class to build your own transformer and integrate into a scikit-learn Pipeline.

An other subpackage is also provided to manage, modify or add parameters such as : regular expressions, keywords, stopwords, etc.

• config : contains ConfigJsonReader class to setup and handle a conf.json file. This JSON file is the core of this package since it's used by different submodules to preprocess the data.

pip install melusine

To use Melusine in a project

import melusine

The basic requirement to use Melusine is to have an input e-mail DataFrame with the following columns:

• body : Body of an email (single message or conversation history)
• header : Header/Subject of an email
• date : Reception date of an email
• from : Email address of the sender
• to : Email address of the recipient
• label (optional): Label of the email for a classification task (examples: Business, Spam, Finance or Family)

To import the test dataset:

from melusine.data.data_loader import load_email_data

df_email = load_email_data()

A working pre-processing pipeline is given below::

from sklearn.pipeline import Pipeline
from melusine.utils.transformer_scheduler import TransformerScheduler
from melusine.prepare_email.manage_transfer_reply import check_mail_begin_by_transfer, update_info_for_transfer_mail, add_boolean_transfer, add_boolean_answer
from melusine.prepare_email.build_historic import build_historic
from melusine.prepare_email.mail_segmenting import structure_email
from melusine.prepare_email.body_header_extraction import extract_last_body
from melusine.prepare_email.cleaning import clean_body

ManageTransferReply = TransformerScheduler(
functions_scheduler=[
    (check_mail_begin_by_transfer, None, ['is_begin_by_transfer']),
    (update_info_for_transfer_mail, None, None),
    (add_boolean_answer, None, ['is_answer']),
    (add_boolean_transfer, None, ['is_transfer'])
])

EmailSegmenting = TransformerScheduler(
functions_scheduler=[
    (build_historic, None, ['structured_historic']),
    (structure_email, None, ['structured_body'])
])

Cleaning = TransformerScheduler(
functions_scheduler=[
    (extract_last_body, None, ['last_body']),
    (clean_body, None, ['clean_body'])
])

prepare_data_pipeline = Pipeline([
  ('ManageTransferReply', ManageTransferReply),
  ('EmailSegmenting', EmailSegmenting),
  ('Cleaning', Cleaning),
])

df_email = prepare_data_pipeline.fit_transform(df_email)

In this example, the pre-processing functions applied are:

• check_mail_begin_by_transfer : Email is a direct transfer (True/False)
• update_info_for_transfer_mail : Update body, header, from, to, date if direct transfer
• add_boolean_answer : Email is an answer (True/False)
• add_boolean_transfer : Email is transferred (True/False)
• build_historic : When email is a conversation, reconstructs the individual message history
• structure_email : Splits each messages into parts and tags them (tags: Hello, Body, Greetings, etc)

A pipeline to train and apply the phraser end tokenizer is given below::

from melusine.nlp_tools.phraser import Phraser, phraser_on_body
from melusine.nlp_tools.tokenizer import Tokenizer

phraser = Phraser(input_column='clean_body')
phraser.train(df_email)

PhraserTransformer = TransformerScheduler(
functions_scheduler=[
    (phraser_on_body, (phraser,), ['clean_body'])
])

phraser_tokenizer_pipeline = Pipeline([
  ('PhraserTransformer', PhraserTransformer),
  ('Tokenizer', Tokenizer(input_column='clean_body'))
])

df_email = phraser_tokenizer_pipeline.fit_transform(df_email)

An example of embedding training is given below::

from melusine.nlp_tools.embedding import Embedding

embedding = Embedding(input_column='clean_body', min_count=10)
embedding.train(df_email)

A pipeline to prepare the metadata is given below:

from melusine.prepare_email.metadata_engineering import MetaExtension, MetaDate, Dummifier

metadata_pipeline = Pipeline([
  ('MetaExtension', MetaExtension()),
  ('MetaDate', MetaDate()),
  ('Dummifier', Dummifier())
])

df_meta = metadata_pipeline.fit_transform(df_email)

An example of keywords extraction is given below::

from melusine.summarizer.keywords_generator import KeywordsGenerator

keywords_generator = KeywordsGenerator()
df_email = keywords_generator.fit_transform(df_email)

An example of classification is given below::

from sklearn.preprocessing import LabelEncoder
from melusine.nlp_tools.embedding import Embedding
from melusine.models.neural_architectures import cnn_model
from melusine.models.train import NeuralModel

X = df_email.drop(['label'], axis=1)
y = df_email.label

le = LabelEncoder()
y = le.fit_transform(y)

pretrained_embedding = embedding

nn_model = NeuralModel(architecture_function=cnn_model,
                       pretrained_embedding=pretrained_embedding,
                       text_input_column='clean_body')
nn_model.fit(X, y)
y_res = nn_model.predict(X)

Because Melusine manipulates pandas dataframes, the naming of the columns is imposed. Here is a basic glossary to provide an understanding of each columns manipulated. Initial columns of the dataframe:

• body : the body of the email. It can be composed of a unique message, a history of messages, a transfer of messages or a combination of history and transfers.
• header : the subject of the email.
• date : the date the email has been sent. It corresponds to the date of the last email message.
• from : the email address of the author of the last email message.
• to : the email address of the recipient of the last email message.

Columns added by Melusine:

• is_begin_by_transfer : boolean, indicates if the email is a direct transfer. In that case it is recommended to update the value of the initial columns with the information of the message transferred.

• is_answer : boolean, indicates if the email contains a history of messages

• is_transfer : boolean, indicates if the email is a transfer (in that case it does not have to be a direct transfer).

• structured_historic : list of dictionaries, each dictionary corresponds to a message of the email. The first dictionary corresponds to the last message (the one that has been written) while the last dictionary corresponds to the first message of the history. Each dictionary has two keys :

  • meta : to access the metadata of the message as a string.
  • text : to access the message itself as a string.

• structured_body : list of dictionaries, each dictionary corresponds to a message of the email. The first dictionary corresponds to the last message (the one that has been written) while the last dictionary corresponds to the first message of the history. Each dictionary has two keys :

  • meta : to access the metadata of the message as a dictionary. The dictionary has three keys:

    • date : the date of the message.
    • from : the email address of the author of the message.
    • to : the email address of the recipient of the message.

  • text : to access the message itself as a dictionary. The dictionary has two keys:

    • header : the subject of the message.
    • structured_text : the different parts of the message segmented and tagged as a list of dictionaries. Each dictionary has two keys:
      • part : to access the part of the message as a string.
      • tags : to access the tag of the part of the message.

• last_body : string, corresponds to the part of the last email message that has been tagged as BODY.

• clean_body : string, corresponds a cleaned last_body.

• clean_header : string, corresponds to a cleaned header.

• clean_text : string, concatenation of clean_header and clean_body.

• tokens : list of strings, corresponds to a tokenized column, by default clean_text.

• keywords : list of strings, corresponds to the keywords of extracted from the tokens column.

Each messages of an email are segmented in the structured_body columns and each part is assigned a tag:

• RE/TR : any metadata such as date, from, to, etc.
• DISCLAIMER : any disclaimer such as L'émetteur décline toute responsabilité....
• GREETINGS : any greetings such as Salutations.
• PJ : any indication of an attached document such as See attached file....
• FOOTER : any footer such as Provenance : Courrier pour Windows.
• HELLO : any salutations such as Bonjour,.
• THANKS : any thanks such as Avec mes remerciements
• BODY : the core of the the message which contains the valuable information.