<?php

echo json_encode( array( array( 'data' => array( array( 'x' => 3, 'y' => 0 ), array( 'x' => 10, 'y' => 0 )) ), array( 'data' => array( array(  'x' => 11, 'y' => 0 ), array( 'x' => 13, 'y' => 0 )) ), array( 'data' => array( array( 'x' => 12, 'y' => 1), array(  'x' => 17, 'y' => 1)))));

[{"data":[{"x":3,"y":0},{"x":10,"y":0}]},{"data":[{"x":11,"y":0},{"x":13,"y":0}]},{"data":[{"x":12,"y":1},{"x":17,"y":1}]}]