feat: Add decimal option to fromCSV.

docs/api/index.md

@@ -128,7 +128,8 @@ This method performs parsing only. To both load and parse a CSV file, use [loadC
 
 * *text*: A string in a delimited-value format.
 * *options*: A CSV format options object:
-  * *delimiter*: A single-character delimiter string between column values.
+  * *delimiter*: A single-character delimiter string between column values (default `','`).
+  * *decimal*: A single-character numeric decimal separator (default `'.'`).
   * *header*: Boolean flag (default `true`) to specify the presence of a  header row. If `true`, indicates the CSV contains a header row with column names. If `false`, indicates the CSV does not contain a header row and the columns are given the names `'col1'`, `'col2'`, and so on.
   * *autoType*: Boolean flag (default `true`) for automatic type inference.
   * *autoMax*: Maximum number of initial rows (default `1000`) to use for type inference.
@@ -148,8 +149,14 @@ aq.fromCSV('a,b\n1,2\n3,4')
 aq.fromCSV('a,b\n00152,2\n30219,4', { parse: { a: String } })
 ```
 
+```js
+// parse semi-colon delimited text with comma as decimal separator
+aq.fromCSV('a;b\nu;-1,23\nv;3,45e5', { delimiter: ';', decimal: ',' })
+```
+
 ```js
 // create table from an input CSV loaded from 'url'
+// alternatively, use the loadCSV method
 aq.fromCSV(await fetch(url).then(res => res.text()))
 ```
 

src/format/from-csv.js

@@ -12,6 +12,7 @@ const DEFAULT_NAME = 'col';
  * Options for CSV parsing.
  * @typedef {object} CSVParseOptions
  * @property {string} [delimiter=','] Single-character delimiter between values.
+ * @property {string} [decimal='.'] Single-character numeric decimal separator.
  * @property {boolean} [header=true] Flag to specify presence of header row.
  *  If true, assumes the CSV contains a header row with column names.
  *  If false, indicates the CSV does not contain a header row, and the
@@ -61,7 +62,7 @@ export default function(text, options = {}) {
   // initialize parsers
   const parsers = options.autoType === false
     ? Array(n).fill(identity)
-    : getParsers(names, values, options.parse);
+    : getParsers(names, values, options);
 
   // apply parsers
   parsers.forEach((parse, i) => {
@@ -84,8 +85,11 @@ export default function(text, options = {}) {
   return new ColumnTable(columns, names);
 }
 
-function getParsers(names, values, opt = {}) {
+function getParsers(names, values, options) {
+  const { parse = {} } = options;
   return names.map(
-    (name, i) => isFunction(opt[name]) ? opt[name] : valueParser(values[i])
+    (name, i) => isFunction(parse[name])
+      ? parse[name]
+      : valueParser(values[i], options)
   );
 }

src/util/parse-values.js

@@ -1,25 +1,33 @@
 import identity from './identity';
 import isISODateString from './is-iso-date-string';
 
-const TYPES = [
-  [ // boolean
-    v => (v === 'true') || (v === 'false'),
-    v => v === 'false' ? false : true
-  ],
-  [ // number
-    v => v === 'NaN' || (v = +v) === v,
-    v => +v
-  ],
-  [ // iso date
-    isISODateString,
-    v => new Date(Date.parse(v))
-  ]
+const parseBoolean = [ // boolean
+  v => (v === 'true') || (v === 'false'),
+  v => v === 'false' ? false : true
 ];
 
-export default function(values) {
-  const n = TYPES.length;
+const parseNumber = [ // number
+  v => v === 'NaN' || (v = +v) === v,
+  v => +v
+];
+
+const parseDate = [ // iso date
+  isISODateString,
+  v => new Date(Date.parse(v))
+];
+
+function numberParser(options) {
+  const { decimal } = options;
+  return decimal && decimal !== '.'
+    ? parseNumber.map(f => s => f(s && s.replace(decimal, '.')))
+    : parseNumber;
+}
+
+export default function(values, options) {
+  const types = [parseBoolean, numberParser(options), parseDate];
+  const n = types.length;
   for (let i = 0; i < n; ++i) {
-    const [test, parser] = TYPES[i];
+    const [test, parser] = types[i];
     if (check(values, test)) {
       return parser;
     }

test/format/from-csv-test.js

@@ -73,4 +73,13 @@ tape('fromCSV parses delimited text with parse option', t => {
   const d = { ...data(), str: ['aa', 'bb', 'cc'] };
   tableEqual(t, table, d, 'csv parsed data with custom parse');
   t.end();
+});
+
+tape('fromCSV parses delimited text with decimal option', t => {
+  tableEqual(t,
+    fromCSV('a;b\nu;-1,23\nv;4,56e5\nw;', { delimiter: ';', decimal: ',' }),
+    { a: ['u', 'v', 'w'], b: [-1.23, 4.56e5, null] },
+    'csv parsed data with decimal option'
+  );
+  t.end();
 });