How can I set random-seed of topic model using mallet in gensim?

Question

I had been trying to keep an output of topic modeling stable by using mallet as a library in gensim. However, I found out that mallet can set random-seed but I do not see any parameter in gensim to set it.

Answer 1

This has just been added to the ldamallet.py wrapper

    def __init__(self, mallet_path, corpus=None, num_topics=100, alpha=50, id2word=None, workers=4, prefix=None,
             optimize_interval=0, iterations=1000, topic_threshold=0.0, random_seed=0):
    """

    Parameters
    ----------
    mallet_path : str
        Path to the mallet binary, e.g. `/home/username/mallet-2.0.7/bin/mallet`.
    corpus : iterable of iterable of (int, int), optional
        Collection of texts in BoW format.
    num_topics : int, optional
        Number of topics.
    alpha : int, optional
        Alpha parameter of LDA.
    id2word : :class:`~gensim.corpora.dictionary.Dictionary`, optional
        Mapping between tokens ids and words from corpus, if not specified - will be inferred from `corpus`.
    workers : int, optional
        Number of threads that will be used for training.
    prefix : str, optional
        Prefix for produced temporary files.
    optimize_interval : int, optional
        Optimize hyperparameters every `optimize_interval` iterations
        (sometimes leads to Java exception 0 to switch off hyperparameter optimization).
    iterations : int, optional
        Number of training iterations.
    topic_threshold : float, optional
        Threshold of the probability above which we consider a topic.
    random_seed: int, optional
        Random seed to ensure consistent results, if 0 - use system clock.

    """

Answer 2

I have had the same issue but to use the latest version of gensim, it is a little bit tricky. As Chris said, the new version has it implemented but running it was troublesome for me. Make sure to do the following as you might be using the old wrapper:

1. conda install -c conda-forge gensim
2. pip install --upgrade gensim

The second step does the job and just installing it won't update the gensim as I had issue with it.

The following links have more info for your question:

Gensim Installation

Mallet Wrapper