datakit/build/cli/reduce.js

Simple JavaScript toolkit for data transform across JSON, CSV and YAML.

"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
exports.documentation = exports.main = void 0;
var io_1 = require("../lib/io");
var user_fn_1 = require("./lib/user-fn");
var verify_1 = require("../lib/verify");
var help_1 = require("./lib/help");
function main(argv) {
    return __awaiter(this, void 0, void 0, function () {
        var _a, fn, details, initialValue, data, reduced;
        return __generator(this, function (_b) {
            switch (_b.label) {
                case 0:
                    _a = (0, user_fn_1.loadUserFn)(argv, "(accumulator, record) => accumulate(accumulator, record)"), fn = _a.fn, details = _a.details;
                    if (argv.length < 1) {
                        throw new Error("Expected argument for initial value.");
                    }
                    initialValue = JSON.parse(argv.shift());
                    return [4 /*yield*/, (0, io_1.inputData)(argv)];
                case 1:
                    data = _b.sent();
                    (0, verify_1.verifyInputArray)(data, "reduce");
                    reduced = data.reduce(function (a, r) { return (0, user_fn_1.invokeUserFn)(function () { return fn(a, r); }, details); }, initialValue);
                    return [4 /*yield*/, (0, io_1.outputData)(argv, reduced)];
                case 2:
                    _b.sent();
                    return [2 /*return*/];
            }
        });
    });
}
exports.main = main;
exports.documentation = {
    name: "reduce",
    desc: "Reduces or aggregates an input dataset to some output value by repeatedly calling the reducer function on every record of the input. Works just like `array.reduce` in JavaScript.",
    syntax: "reduce <reducer-fn> <seed-value> [<input-file>] [<output-file>]",
    inputs: help_1.standardCmdInputs,
    outputs: help_1.standardCmdOutputs,
    args: [
        {
            name: "reducer-fn",
            desc: "A JavaScript \"reducer\" function called for each record of the input dataset. Specifying a file name will load the JavaScript code from the file.",
        },
        {
            name: "seed-value",
            desc: "JSON value that is used as the initial accumulator value for the reduction."
        },
        help_1.standardInputFileHelp,
        help_1.standardOutputFileHelp,
    ],
    examples: [
        {
            name: "Reads JSON data from standard input, applies the reduction to compute total sales and writes to standard output",
            cmd: 'command-that-produces-json | reduce "(a, r) => a + r.sales" 0',
        },
        {
            name: "Reads data from a file, applies the reduction and writes to standard output",
            cmd: 'reduce "(a, r) => a + r.sales" 0 input-file.json',
        },
        {
            name: "Reads data from a file, applies the reduction and writes output to another file",
            cmd: 'reduce "(a, r) => a + r.sales" 0 input-file.csv output-file.csv'
        },
        {
            name: "Reads JSON data from standard input, applies the reduction and writes output to another file",
            cmd: 'command-that-produces-json | reduce "(a, r) => a + r.sales" 0 - output-file.csv'
        },
        {
            name: "Loads a JavaScript file for the transformation",
            cmd: 'reduce input-file.yaml my-reducer.js 0',
        },
    ],
};
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