import readData from '../readers/readData'
import parserTsv from '../parsers/tsv'
/**
* Asynchronously read a tab-separated value file. Returns an empty array if file is empty.
*
* @function readTsv
* @param {String} filePath Input file path
* @param {Function|Object} [map] Optional map function or an object with `map` key that is a function. Called once for each row with the signature `(row, i)` and must return the transformed row. See example below or d3-dsv documentation for details.
* @param {Function} callback Has signature `(err, data)`
*
* @example
* io.readTsv('path/to/data.tsv', function (err, data) {
* console.log(data) // Json data
* })
*
* // Transform values on load
* io.readTsv('path/to/data.tsv', function (row, i, columns) {
* console.log(columns) // [ 'name', 'occupation', 'height' ]
* row.height = +row.height // Convert this value to a number
* return row
* }, function (err, data) {
* console.log(data) // Json data with casted values
* })
*/
export default function readTsv (filePath, opts_, cb) {
var parserOptions
if (typeof cb === 'undefined') {
cb = opts_
} else {
parserOptions = typeof opts_ === 'function' ? {map: opts_} : opts_
}
readData(filePath, {parser: parserTsv, parserOptions: parserOptions}, cb)
}
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