From 72a2047a5658b27df4886112b97842079788189b Mon Sep 17 00:00:00 2001
From: Prashant Patel <prashant12290@yahoo.co.in>
Date: Mon, 27 Nov 2017 15:50:11 +0530
Subject: [PATCH 1/2] add legend format

---
 c3.js | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/c3.js b/c3.js
index d607b1772..e65dcdbae 100644
--- a/c3.js
+++ b/c3.js
@@ -1,7 +1,7 @@
 (function (global, factory) {
-	typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
-	typeof define === 'function' && define.amd ? define(factory) :
-	(global.c3 = factory());
+    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
+    typeof define === 'function' && define.amd ? define(factory) :
+    (global.c3 = factory());
 }(this, (function () { 'use strict';
 
 var CLASS = {
@@ -5097,6 +5097,7 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         legend_padding: 0,
         legend_item_tile_width: 10,
         legend_item_tile_height: 10,
+        legend_format: undefined,
         // axis
         axis_rotated: false,
         axis_x_show: true,
@@ -7431,8 +7432,12 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
             $$.api.revert();
         }
     });
-    l.append('text').text(function (id) {
-        return isDefined(config.data_names[id]) ? config.data_names[id] : id;
+    l.append('text').text(function (id, index) {
+        if(config.legend_format && isFunction(config.legend_format)) {
+            return config.legend_format(id, index);
+        } else {
+            return isDefined(config.data_names[id]) ? config.data_names[id] : id;
+        }
     }).each(function (id, i) {
         updatePositions(this, id, i);
     }).style("pointer-events", "none").attr('x', $$.isLegendRight || $$.isLegendInset ? xForLegendText : -200).attr('y', $$.isLegendRight || $$.isLegendInset ? -200 : yForLegendText);
@@ -7445,8 +7450,12 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
         background = $$.legend.insert('g', '.' + CLASS.legendItem).attr("class", CLASS.legendBackground).append('rect');
     }
 
-    texts = $$.legend.selectAll('text').data(targetIds).text(function (id) {
-        return isDefined(config.data_names[id]) ? config.data_names[id] : id;
+    texts = $$.legend.selectAll('text').data(targetIds).text(function (id, index) {
+        if(config.legend_format && isFunction(config.legend_format)) {
+            return config.legend_format(id, index);
+        } else {
+            return isDefined(config.data_names[id]) ? config.data_names[id] : id;
+        }
     } // MEMO: needed for update
     ).each(function (id, i) {
         updatePositions(this, id, i);

From 47bdff98994dbf89a85a85e3b25cce28fdfb99b6 Mon Sep 17 00:00:00 2001
From: Prashant Patel <prashant12290@yahoo.co.in>
Date: Sun, 15 Apr 2018 10:36:50 +0530
Subject: [PATCH 2/2] make the changes asked

---
 src/config.js | 1 +
 src/legend.js | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/config.js b/src/config.js
index 54b010fd7..cd3536944 100644
--- a/src/config.js
+++ b/src/config.js
@@ -91,6 +91,7 @@ c3_chart_internal_fn.getDefaultConfig = function () {
         legend_padding: 0,
         legend_item_tile_width: 10,
         legend_item_tile_height: 10,
+        legend_format: undefined,
         // axis
         axis_rotated: false,
         axis_x_show: true,
diff --git a/src/legend.js b/src/legend.js
index 1f4ec73a4..40769e446 100644
--- a/src/legend.js
+++ b/src/legend.js
@@ -264,7 +264,13 @@ c3_chart_internal_fn.updateLegend = function (targetIds, options, transitions) {
             }
         });
     l.append('text')
-        .text(function (id) { return isDefined(config.data_names[id]) ? config.data_names[id] : id; })
+        .text(function (id, index) {
+            if(config.legend_format && isFunction(config.legend_format)) {
+                return config.legend_format(id, index);
+            } else {
+                return isDefined(config.data_names[id]) ? config.data_names[id] : id;
+            }
+        })
         .each(function (id, i) { updatePositions(this, id, i); })
         .style("pointer-events", "none")
         .attr('x', $$.isLegendRight || $$.isLegendInset ? xForLegendText : -200)