VU-lexicon-propagation_kernel

These scripts implement the propagation algorithm for automatically generation of sentiment lexicons from WordNet. There are two main scripts to generate a lexicon:

1. propagate_wn.py --> this script propagates a list of seeds over WordNet and generates and intermediate CSV format
2. from_csv_to_lmf.py --> this script reads the previous CSV format and generates the final Opener-LMF lexicon

Some other scripts are included in the repository:

1. csv_from_synset_to_lemma.py --> transforms a synset-based CSV into a lemma-based CSV lexicon
2. validate.py --> validate a LMF lexicon against the opener_lmf.dtd DTD

Installation and requirements

The scripts are Python, so you need to have Python installed in your machine (version >=2.6). Also you need the lxml library for XML processing. To install this requirement, you can just run:

$ pip install -r requirements.txt

There is nothing else required to run these scripts.

General Approach

The general approach to generate a lexicon these are the required steps:

1. Get the WordNet in LMF format for your language
2. Generate/translate a list of seeds
3. Create the list with the relations you want to use for the propagation
4. Run the script propagate_wn.py to generate the CSV file
5. Optionally convert the synset-based CSV file into a lemma-based CSV file with the script (csv_from_synset_to_lemma.py)
6. Manually check the most frequent words of your language and modify that CSV file
7. From the corrected CSV, with the from_csv_to_lmf.py script, generate the final LMF lexicon

Seed list

The seed list has to be stored in a file, wit a seed per line, with the format: synset/polarity/pos

For instance:
n_n-531677/negative/n
n_n-531685/neutral/n
n_n-531697/positive/n
n_n-531759/negative/n
n_n-531792/neutral/n
n_n-531952/neutral/n
......

The seed list can be based also in sense identifiers instead of synset identifiers, but the use of synsets ids is strongly recommended.

Relations file

The WordNet relations that you want to use for the propagation have to be stored in a file. You have to be sure that the labels for the relations match with the labels of the relations in your WordNet. You have to associate a weight to each relation, that will represent how the strength of a polarity is modified when it is propagated through that relation. For instance: we have a synset with a positive polarity with strength 3, and we propagate this positive polarity to all its hyponyms. In the relations file we defined a weight to 0.1 for HYPONYMY, so all the hyponyms will get a positive polarity with a weight of 0.3 (3*0.1). If the weight is negative, we will invert the polarity when propagation throught that kind of relations

In our experiments, we have used the following configuration for the relations file with good results, so it could be a good idea to use also these relations addapted to your own labels in case they differ.

NEAR_SYNONYM 2
NEAR_ANTONYM -2
HAS_HYPONYM 1
HAS_HYPERONYM 0.5

Script propagate_wn.py

You can get the usage of this script by simply running:

$ python propagate_wn.py -h

The options and parameters for this script are the following:

• Required:

  • --wn=FILE file with wordnet in LMF format
  • --seed-list=FILE file with list of seeds with polarities
  • --relations=FILE file with relations and weights
  • --out=FILE file to store the results in CSV format
  • --seed-sense In case your seed list is based on senses and not synsets

• Optional:

  • --log=FILE Filename where store the log (default no log)
  • --max-depth=INT Maximum depth in number of relations to expand each synset (default 5)

Example:

$ python propagate_wn.py  --wn=cornetto.lmf.xml --seed-list=file_seeds.txt --relations=my_rels.txt --out my_output.csv

Script csv_from_synset_to_lemma.py

This script reads the synset based CSV and generates the a CSV based on lemmas. For this, the different polarities assigned to each synset for a specific lemma are collected and some heuristic is applied to generate an accumulated. Two heuristics have been implemented:

• Average: the average for each polarity is obtained using the confidence for each synset of the lemma
• Most confidence: the polarity with a higher confidence is assigned

This script reads from the standard input and writes to the standard output, and also generates some log information on the error output, so for calling it from the command line:

$ cat polarities-synset.csv | python csv_from_synset_to_lemma.py > polarities-lemma.csv 2> polarities-lemma.log

Script from_csv_to_lmf.py

This script reads the CSV and generates the final Opener-LMF format. To run the program:

$ cat my_output.csv | python from_csv_to_lmf.py > my_lexicon.lmf

There is one option (-verbose) you can set to the program:

$ cat my_output.csv | python from_csv_to_lmf.py -verbose > my_lexicon.lmf

With the verbose option we will create one lexical entry for each lemma. So for instance if we have in our CSV output: n_n-526797;N;neutral;0.5;scheepmaker,scheepsbouwer,scheepsmaker

This means that the synset n_n-526797, which is a noun (N), has a neutral polarity with strength 0.5, and the words in this synset are three:scheepmaker, scheepsbouwer and scheepsmaker. If we create the LMF lexicon without the verbos option, there will be only one lexical entry for scheepmaker, with the synset n_n-526797 and the neutral polarity associated (The polarity actually is linked to the synset and not to the word). With the verbose option, we will have three lexical entries, one for each word in the synset, with the same information.

This scripts generates LMF lexicons that comply with the DTD included in the repository (opener_lmf.dtd). If you want to check that the lexicon generate is really following the structure defined in the DTD, you can use the script validate.py:

$ cat lexicon.lmf | validate.py

You will get a message with the status of the validation, and the errors in case there is something wrong.

Sentiment modifiers

The previous script from_csv_to_lmf.py also consider that the input CSV can contain sentiment modifiers like polarity shifters, intensifiers or weakeners, so all this information will be stored in the final LMF lexicon. To incorporate this information to the CSV files, we should include one extra line for each modifier, with the following information and format:

unknown;ADV;neutral;1;very;-1;intensifier

So the format is the same as for polarity words, but with one extra field at the end containing the modifier for the word. In this case the synset(unknown), the polarity(neutral) and the score(1) specified in the CSV will not be used in the LMF, and the lexical entry will appear as a manual annotation.

Contact

• Ruben Izquierdo
• Vrije University of Amsterdam
• ruben.izquierdobevia@vu.nl