Add dsv.formatBody. Fixes #34.

README.md

@@ -43,43 +43,51 @@ var data = d3.csvParse(string);
 
 ## API Reference
 
-<a name="csvParse" href="#csvParse">#</a> d3.<b>csvParse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js#L5 "Source")
+<a name="csvParse" href="#csvParse">#</a> d3.<b>csvParse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)(",").[parse](#dsv_parse).
 
-<a name="csvParseRows" href="#csvParseRows">#</a> d3.<b>csvParseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js#L6 "Source")
+<a name="csvParseRows" href="#csvParseRows">#</a> d3.<b>csvParseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)(",").[parseRows](#dsv_parseRows).
 
-<a name="csvFormat" href="#csvFormat">#</a> d3.<b>csvFormat</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js#L7 "Source")
+<a name="csvFormat" href="#csvFormat">#</a> d3.<b>csvFormat</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)(",").[format](#dsv_format).
 
-<a name="csvFormatRows" href="#csvFormatRows">#</a> d3.<b>csvFormatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js#L8 "Source")
+<a name="csvFormatBody" href="#csvFormatBody">#</a> d3.<b>csvFormatBody</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js "Source")
+
+Equivalent to [dsvFormat](#dsvFormat)(",").[formatBody](#dsv_formatBody).
+
+<a name="csvFormatRows" href="#csvFormatRows">#</a> d3.<b>csvFormatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/csv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)(",").[formatRows](#dsv_formatRows).
 
-<a name="tsvParse" href="#tsvParse">#</a> d3.<b>tsvParse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js#L5 "Source")
+<a name="tsvParse" href="#tsvParse">#</a> d3.<b>tsvParse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)("\t").[parse](#dsv_parse).
 
-<a name="tsvParseRows" href="#tsvParseRows">#</a> d3.<b>tsvParseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js#L6 "Source")
+<a name="tsvParseRows" href="#tsvParseRows">#</a> d3.<b>tsvParseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)("\t").[parseRows](#dsv_parseRows).
 
-<a name="tsvFormat" href="#tsvFormat">#</a> d3.<b>tsvFormat</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js#L7 "Source")
+<a name="tsvFormat" href="#tsvFormat">#</a> d3.<b>tsvFormat</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)("\t").[format](#dsv_format).
 
-<a name="tsvFormatRows" href="#tsvFormatRows">#</a> d3.<b>tsvFormatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js#L8 "Source")
+<a name="tsvFormatBody" href="#tsvFormatBody">#</a> d3.<b>tsvFormatBody</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js "Source")
+
+Equivalent to [dsvFormat](#dsvFormat)("\t").[formatBody](#dsv_formatBody).
+
+<a name="tsvFormatRows" href="#tsvFormatRows">#</a> d3.<b>tsvFormatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/tsv.js "Source")
 
 Equivalent to [dsvFormat](#dsvFormat)("\t").[formatRows](#dsv_formatRows).
 
-<a name="dsvFormat" href="#dsvFormat">#</a> d3.<b>dsvFormat</b>(<i>delimiter</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js#L30)
+<a name="dsvFormat" href="#dsvFormat">#</a> d3.<b>dsvFormat</b>(<i>delimiter</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js)
 
 Constructs a new DSV parser and formatter for the specified *delimiter*. The *delimiter* must be a single character (*i.e.*, a single 16-bit code unit); so, ASCII delimiters are fine, but emoji delimiters are not.
 
-<a name="dsv_parse" href="#dsv_parse">#</a> *dsv*.<b>parse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js#L34 "Source")
+<a name="dsv_parse" href="#dsv_parse">#</a> *dsv*.<b>parse</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js "Source")
 
 Parses the specified *string*, which must be in the delimiter-separated values format with the appropriate delimiter, returning an array of objects representing the parsed rows.
 
@@ -123,7 +131,7 @@ var data = d3.csvParse(string, function(d) {
 
 Note: using `+` rather than [parseInt](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt) or [parseFloat](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseFloat) is typically faster, though more restrictive. For example, `"30px"` when coerced using `+` returns `NaN`, while parseInt and parseFloat return `30`.
 
-<a name="dsv_parseRows" href="#dsv_parseRows">#</a> <i>dsv</i>.<b>parseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js#L43 "Source")
+<a name="dsv_parseRows" href="#dsv_parseRows">#</a> <i>dsv</i>.<b>parseRows</b>(<i>string</i>[, <i>row</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js "Source")
 
 Parses the specified *string*, which must be in the delimiter-separated values format with the appropriate delimiter, returning an array of arrays representing the parsed rows.
 
@@ -160,7 +168,7 @@ var data = d3.csvParseRows(string, function(d, i) {
 
 In effect, *row* is similar to applying a [map](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/map) and [filter](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/filter) operator to the returned rows.
 
-<a name="dsv_format" href="#dsv_format">#</a> <i>dsv</i>.<b>format</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js#L105 "Source")
+<a name="dsv_format" href="#dsv_format">#</a> <i>dsv</i>.<b>format</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js "Source")
 
 Formats the specified array of object *rows* as delimiter-separated values, returning a string. This operation is the inverse of [*dsv*.parse](#dsv_parse). Each row will be separated by a newline (`\n`), and each column within each row will be separated by the delimiter (such as a comma, `,`). Values that contain either the delimiter, a double-quote (`"`) or a newline will be escaped using double-quotes.
 
@@ -172,7 +180,11 @@ var string = d3.csvFormat(data, ["year", "make", "model", "length"]);
 
 All fields on each row object will be coerced to strings. If the field value is null or undefined, the empty string is used. If the field value is a Date, the ISO 8601 date format is used per [*date*.toISOString](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString). For more control over which and how fields are formatted, first map *rows* to an array of array of string, and then use [*dsv*.formatRows](#dsv_formatRows).
 
-<a name="dsv_formatRows" href="#dsv_formatRows">#</a> <i>dsv</i>.<b>formatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js#L114 "Source")
+<a name="dsv_formatBody" href="#dsv_formatBody">#</a> <i>dsv</i>.<b>formatBody</b>(<i>rows</i>[, <i>columns</i>]) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js "Source")
+
+Equivalent to [*dsv*.format](#dsv_format), but omits the header row. This is useful, for example, when appending rows to an existing file.
+
+<a name="dsv_formatRows" href="#dsv_formatRows">#</a> <i>dsv</i>.<b>formatRows</b>(<i>rows</i>) [<>](https://github.com/d3/d3-dsv/blob/master/src/dsv.js "Source")
 
 Formats the specified array of array of string *rows* as delimiter-separated values, returning a string. This operation is the reverse of [*dsv*.parseRows](#dsv_parseRows). Each row will be separated by a newline (`\n`), and each column within each row will be separated by the delimiter (such as a comma, `,`). Values that contain either the delimiter, a double-quote (") or a newline will be escaped using double-quotes.
 

src/csv.js

@@ -5,4 +5,5 @@ var csv = dsv(",");
 export var csvParse = csv.parse;
 export var csvParseRows = csv.parseRows;
 export var csvFormat = csv.format;
+export var csvFormatBody = csv.formatBody;
 export var csvFormatRows = csv.formatRows;

src/dsv.js

@@ -95,13 +95,22 @@ export default function(delimiter) {
     return rows;
   }
 
-  function format(rows, columns) {
-    if (columns == null) columns = inferColumns(rows);
-    return [columns.map(formatValue).join(delimiter)].concat(rows.map(function(row) {
+  function preformatBody(rows, columns) {
+    return rows.map(function(row) {
       return columns.map(function(column) {
         return formatValue(row[column]);
       }).join(delimiter);
-    })).join("\n");
+    });
+  }
+
+  function format(rows, columns) {
+    if (columns == null) columns = inferColumns(rows);
+    return [columns.map(formatValue).join(delimiter)].concat(preformatBody(rows, columns)).join("\n");
+  }
+
+  function formatBody(rows, columns) {
+    if (columns == null) columns = inferColumns(rows);
+    return preformatBody(rows, columns).join("\n");
   }
 
   function formatRows(rows) {
@@ -123,6 +132,7 @@ export default function(delimiter) {
     parse: parse,
     parseRows: parseRows,
     format: format,
+    formatBody: formatBody,
     formatRows: formatRows
   };
 }

src/index.js

@@ -1,4 +1,4 @@
 export {default as dsvFormat} from "./dsv";
-export {csvParse, csvParseRows, csvFormat, csvFormatRows} from "./csv";
-export {tsvParse, tsvParseRows, tsvFormat, tsvFormatRows} from "./tsv";
+export {csvParse, csvParseRows, csvFormat, csvFormatBody, csvFormatRows} from "./csv";
+export {tsvParse, tsvParseRows, tsvFormat, tsvFormatBody, tsvFormatRows} from "./tsv";
 export {default as autoType} from "./autoType";

src/tsv.js

@@ -5,4 +5,5 @@ var tsv = dsv("\t");
 export var tsvParse = tsv.parse;
 export var tsvParseRows = tsv.parseRows;
 export var tsvFormat = tsv.format;
+export var tsvFormatBody = tsv.formatBody;
 export var tsvFormatRows = tsv.formatRows;

test/csv-test.js

@@ -299,6 +299,16 @@ tape("csvFormat(array, columns) coerces field values to strings", function(test)
   test.end();
 });
 
+tape("csvFormatBody(array) omits the header row", function(test) {
+  test.deepEqual(dsv.csvFormatBody([{a: 1, b: 2}, {c: 3, b: 4}, {c: 5, a: 1, b: 2}]), "1,2,\n,4,3\n1,2,5");
+  test.end();
+});
+
+tape("csvFormatBody(array, columns) omits the header row", function(test) {
+  test.deepEqual(dsv.csvFormatBody([{a: 1, b: 2}, {c: 3, b: 4}, {c: 5, a: 1, b: 2}], ["a", "b"]), "1,2\n,4\n1,2");
+  test.end();
+});
+
 tape("csvFormatRows(array) takes an array of array of string as input", function(test) {
   test.deepEqual(dsv.csvFormatRows([["a", "b", "c"], ["1", "2", "3"]]), "a,b,c\n1,2,3");
   test.end();