From f1107b11af162bbf2b3a4af723efc2229d01387d Mon Sep 17 00:00:00 2001
From: Tomas Tomecek <ttomecek@redhat.com>
Date: Thu, 18 Aug 2016 10:39:00 +0200
Subject: [PATCH] add source_index to targets

this is very useful in callbacks so you can access source data
and use those in the callbacks

Fixes #1809
---
 src/data.convert.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/data.convert.js b/src/data.convert.js
index 8c523f5..090041c 100644
--- a/src/data.convert.js
+++ b/src/data.convert.js
@@ -189,7 +189,14 @@ c3_chart_internal_fn.convertDataToTargets = function (data, appendXs) {
 
     // finish targets
     targets.forEach(function (t) {
-        var i;
+        var i = 0;
+        // index values by index in input data, e.g. json
+        // this is very useful in callbacks so you can access source data
+        // and use those in the callbacks
+        t.values.forEach(function (v) {
+            v.source_index = i++;
+        });
+
         // sort values by its x
         if (config.data_xSort) {
             t.values = t.values.sort(function (v1, v2) {