Export and import transition table as json for Markov and DeepMarkov

[tmhglnd]

For the normal Markov this will be quite straight forward, for the DeepMarkov it needs some translation because that class uses the Map object. Below some code that should be implemented from https://stackoverflow.com/questions/29085197/how-do-you-json-stringify-an-es6-map:

// when exporting
JSON.stringify(markov.table, replacer);

// when importing
markov.table = JSON.parse(inputJSON, reviver);

// function for stringifying the Map output to store as json
function replacer(key, value) {
    if (value instanceof Map) {
        return {
            type: 'Map',
            value: [ ...value ],
        };
    } else {
        return value;
    }
}

// function for parsing a stringified Map output stored as json
function reviver(key, value) {
    if (typeof value === 'object' && value !== null) {
        if (value.type === 'Map') {
            return new Map(value.value);
        }
    }
    return value;
}

[tmhglnd]

For MarkovChain() there is now an markov.read() method to set the transition table.

[tmhglnd]

This is now fixed in 7211cf46a1a096b705eab5ee3e20554b2f8897fc. The methods .stringify() and .parse() have been added to the DeepMarkovChain class. See more details in the docs: https://github.com/tmhglnd/total-serialism/blob/master/docs/stochastic-methods.md#deepmarkovchain