Merge pull request #7 from zivkovicp/add-transpose

Add transpose method

README.md

@@ -287,4 +287,12 @@ exists
 SimpleArrayLibrary::setColumn(array(array('foo' => 2), array()), 'foo', 1); // array(array('foo' => 1), array('foo' => 1))
 SimpleArrayLibrary::setColumn(array(array('foo' => 2), array()), 'foo', 1, false, false); // array(array('foo' => 2), array())
 SimpleArrayLibrary::setColumn(array(array('foo' => 2), array()), 'foo', 1, true, false); // array(array('foo' => 2), array('foo' => 1))
+```
+transpose
+------------------------------
+Transpose a matrix
+
+Turns rows into columns, and columns into rows. This is very handy when you need to reshape a dataset for a report or plot.
+```php
+SimpleArrayLibrary::transpose(array(array(1, 2, 3). array(4, 5, 6))); // array(array(1, 4), array(2, 5), array(3, 6))
 ```

src/Categories/Changers.php

@@ -181,4 +181,17 @@ public static function setColumn(array $matrix, $column, $value, $insertIfMissin
 
         return $matrix;
     }
+
+    /**
+     * @param array $matrix
+     *
+     * @return array
+     */
+    public static function transpose(array $matrix)
+    {
+        // example #4 explains how this works
+        // http://php.net/manual/en/function.array-map.php
+        array_unshift($matrix, null);
+        return call_user_func_array('array_map', $matrix);
+    }
 }

test/SimpleArrayLibrary/TransposeTest.php

@@ -0,0 +1,41 @@
+<?php
+
+use SimpleArrayLibrary\SimpleArrayLibrary;
+
+class TransposeTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @param array $data
+     *
+     * @return void
+     * @dataProvider getData
+     */
+    public function test_function(array $data)
+    {
+        // invoke logic & test
+        $this->assertEquals($data['expResult'], SimpleArrayLibrary::transpose($data['matrix']));
+    }
+
+    /**
+     * @return array
+     */
+    public function getData()
+    {
+        return array(
+            // #0 column required & present
+            array(
+                array(
+                    'matrix' => array(
+                        array(1, 2, 3),
+                        array(4, 5, 6)
+                    ),
+                    'expResult' => array(
+                        array(1, 4),
+                        array(2, 5),
+                        array(3, 6)
+                    )
+                )
+            )
+        );
+    }
+}