42 lines
1.1 KiB
JavaScript
42 lines
1.1 KiB
JavaScript
const fs = require('fs');
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// formats for the data parameter in the function below: {col1: array | function, col2: array | function}
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function addCols(path, data) {
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let csv = fs.readFileSync(path, 'utf8');
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csv = csv.split('\n').map(line => line.trim());
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let colNames = Object.keys(data);
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for (let i = 0; i < colNames.length; i++) {
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let c = colNames[i];
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if (typeof data[c] === 'function') {
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csv = csv.map((line, idx) => idx === 0
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? line + ',' + c
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: line + ',' + data[c](line, idx)
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);
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} else if (Array.isArray(data[c])) {
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csv = csv.map((line, idx) => idx === 0
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? line + ',' + c
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: line + ',' + data[c][idx - 1]
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);
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}
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}
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fs.createWriteStream(path, {
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flag: 'w',
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defaultEncoding: 'utf8'
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}).end(csv.join('\n'));
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}
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addCols('test.csv', {
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sum: function (line, idx) {
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let s = 0;
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line = line.split(',').map(d => +(d.trim()));
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for (let i = 0; i < line.length; i++) {
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s += line[i];
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}
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return s;
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},
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id: function(line, idx) {
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return idx;
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}
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});
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