README

arff-utils

a package for creating arff files for use in WEKA machine learning

usage

var Arff = require('arff-utils');
var arff = new Arff.ArffWriter("relation name");
arff.addNumericAttribute("num");
arff.addStringAttribute("str");
arff.addNominalAttribute("nom", ["a", "b", "c"]);
arff.addDateAttribute("dt");
arff.addData([1,"s","a","2001-04-03 12:12:12"]);
arff.writeToStream(process.stdout);

ctor

new Arff.ArffWriter(relation[, mode][, options])

relation relation name
mode [optional] if entering data manually with addData one must state the type of data that will be added. The type can be of [Arff.MODE_OBJECT, Arff.MODE_ARRAY, Arff.MODE_CSV]. default value is MODE_ARRAY. see below in examples for usage of each one.
options [optional]
- reduce an object mapping nominal values that should be transformed to a different value. For example { "false":"f" } will transform all the nominal values "false" to "f" to instead
- skipRedundantNominal boolean whether to skip nominal attributes with only a single value. If true these will be omitted from the final output. default is false.

adding attributes

all attribute adding functions receive a string as the first parameter - the name of the attribute.

addNumericAttribute

arff.addNumericAttribute(name);

Add a new numeric attribute. This attribute can be of real or integer - it doesnt matter.

addStringAttribute

arff.addStringAttribute(name);

Add a new string attribute.

addNominalAttribute

arff.addNominalAttribute(name, values);

Adds a new nominal attribute. Receives an array of string values for this attribute as the second parameter.

addDateAttribute

arff.addDateAttribute(name[, format]);

Adds a new date attribute. Receives an optional second parameter of type string as the date format as stated by the arff specs.

addData(data)

data should be in the format as specified in the constructor.

for MODE_ARRAY (default) data should be an array exactly the size of the number of attributes
for mode MODE_OBJECT data should be an object where the property keys are the attribute names and they must match the number of attributes exactly
for mode MODE_CSV data should be a comma delimited string with the values matching exactly the number of attributes.

After addData is called for the first time you can not add any new attributes.

writeToStream(stream)

writes the arff content into the supplied stream

parseCsv(in, out[, options])

Given the data in csv format parseCsv will iterate thru the csv and output an arff file.

in - filename or input stream to read csv from
out - stream to write output arff
options - [optional]
- start - what line to start reading the input csv from (default is zero)
- count - how many lines to read from the input csv (default is until the end)
- autoNominals - boolean. If true nominal values will be automatically determined from the set of available values in the data. default is false.

examples

var arff = new Arff.ArffWriter("myarff", Arff.MODE_OBJECT);
arff.addNumericAttribute("num");
arff.addStringAttribute("str");
arff.addNominalAttribute("nom", ["a", "b", "c d"]);
arff.addDateAttribute("dt");
arff.addDateAttribute("dtf", "yy mm dd");

arff.addData({
    num: 1,
    str: "s",
    nom: "a",
    dt: "2001-04-03 12:12:12",
    dtf: "2001-04-03 12:12:12"
});
arff.addData({
    num: 2,
    str: "s2",
    nom: "c d",
    dt: "2015-04-03 12:12:12",
    dtf: "2001-04-03 12:12:12"
});

arff.writeToStream(process.stdout);

var arff = new Arff.ArffWriter("myarff", Arff.MODE_ARRAY);
arff.addNumericAttribute("num");
arff.addStringAttribute("str");
arff.addNominalAttribute("nom", ["a", "b", "c d"]);
arff.addDateAttribute("dt");
arff.addDateAttribute("dtf", "yy mm dd");

arff.addData([1, "s", "a", "2001-04-03 12:12:12", "2001-04-03 12:12:12"]);
arff.addData([2, "s s", "c d", "2009-04-12 12:12:12", "2001-04-03 12:12:12"]);

arff.writeToStream(process.stdout);

var arff = new Arff.ArffWriter("myarff", Arff.MODE_CSV, {     
    reduce: {
        "c d": "c" 
    }
});
arff.addNumericAttribute("num");
arff.addStringAttribute("str");
arff.addNominalAttribute("nom", ["a", "b", "c d"]);
arff.addDateAttribute("dt");
arff.addDateAttribute("dtf", "yy mm dd");

arff.addData('1,s,a,"2001-04-03 12:12:12","2001-04-03 12:12:12"');
arff.addData('2,"s s","c d","2011-04-03 12:12:12","2001-04-03 12:12:12"');

arff.writeToStream(process.stdout);

var arff = new Arff.ArffWriter("parsearf");
arff.addNumericAttribute("num");
arff.addStringAttribute("str");
arff.addNominalAttribute("nom");
arff.addDateAttribute("dt");

//read lines 1 - 4 from test.csv and auto insert nominal values according to data:
arff.parseCsv('test.csv', process.stdout, {
    autoNominals: true,
    start: 1,
    count: 3
});

Usage no npm install needed!