add prop separatethousands to layout_attributes

Author: satotake

src/plots/cartesian/axes.js

@@ -1092,7 +1092,8 @@ function numFormat(v, ax, fmtoverride, hover) {
         tickRound = ax._tickround,
         exponentFormat = fmtoverride || ax.exponentformat || 'B',
         exponent = ax._tickexponent,
-        tickformat = ax.tickformat;
+        tickformat = ax.tickformat,
+        separatethousands = ax.separatethousands;
 
     // special case for hover: set exponent just for this value, and
     // add a couple more digits of precision over tick labels
@@ -1156,7 +1157,7 @@ function numFormat(v, ax, fmtoverride, hover) {
             if(dp) v = v.substr(0, dp + tickRound).replace(/\.?0+$/, '');
         }
         // insert appropriate decimal point and thousands separator
-        v = Lib.numSeparate(v, ax._gd._fullLayout.separators);
+        v = Lib.numSeparate(v, ax._gd._fullLayout.separators, separatethousands);
     }
 
     // add exponent

src/plots/cartesian/layout_attributes.js

@@ -310,6 +310,14 @@ module.exports = {
             'If *B*, 1B.'
         ].join(' ')
     },
+    separatethousands: {
+        valType: 'boolean',
+        dflt: false,
+        role: 'style',
+        description: [
+            'even 4-digit integers are separated if true'
+        ].join(' ')
+    },
     tickformat: {
         valType: 'string',
         dflt: '',

src/plots/cartesian/tick_label_defaults.js

@@ -43,6 +43,7 @@ module.exports = function handleTickLabelDefaults(containerIn, containerOut, coe
             if(!tickFormat && axType !== 'date') {
                 coerce('showexponent', showAttrDflt);
                 coerce('exponentformat');
+                coerce('separatethousands');
             }
         }
     }