Gridlines use exponent base

mdtusz · mdtusz · commit 4cb21925daff · 2016-02-12T17:11:33.000-05:00
diff --git a/src/plots/cartesian/axes.js b/src/plots/cartesian/axes.js
@@ -649,9 +649,9 @@ axes.autoTicks = function(ax, roughDTick){
         ax.dtick = Math.ceil(Math.max(roughDTick, 1));
     }
     else{
-        // auto ticks always start at 0
+        // auto ticks always start at 0 and increment
         ax.tick0 = 0;
-        base = Math.pow(10, Math.floor(Math.log(roughDTick) / Math.LN10));
+        base = Math.pow(ax.exponentbase, Math.floor(Math.log(roughDTick) / Math.log(ax.exponentbase)));
         ax.dtick = roundDTick(roughDTick, base, roundBase10);
     }
 
@@ -1013,12 +1013,13 @@ function formatLinear(ax, out, hover, extraPrecision, hideexp) {
 // also automatically switch to sci. notation
 var SIPREFIXES = ['f', 'p', 'n', '&mu;', 'm', '', 'k', 'M', 'G', 'T'];
 function numFormat(v, ax, fmtoverride, hover) {
-        // negative?
+    // negative?
     var isNeg = v < 0,
         // max number of digits past decimal point to show
         tickRound = ax._tickround,
         exponentFormat = fmtoverride || ax.exponentformat || 'B',
         exponent = ax._tickexponent,
+        base = ax.exponentbase || 10,
         tickformat = ax.tickformat;
 
     // special case for hover: set exponent just for this value, and
@@ -1027,6 +1028,7 @@ function numFormat(v, ax, fmtoverride, hover) {
         // make a dummy axis obj to get the auto rounding and exponent
         var ah = {
             exponentformat:ax.exponentformat,
+            exponentbase: ax.exponentbase,
             dtick: ax.showexponent==='none' ? ax.dtick :
                 (isNumeric(v) ? Math.abs(v) || 1 : 1),
             // if not showing any exponents, don't change the exponent
diff --git a/src/plots/cartesian/layout_attributes.js b/src/plots/cartesian/layout_attributes.js
@@ -288,6 +288,15 @@ module.exports = {
             'If *B*, 1B.'
         ].join(' ')
     },
+    exponentbase: {
+        valType: 'number',
+        min: 0,
+        dflt: 10
+        role: 'style',
+        description: [
+            'Determines the base for axes and exponent labels.'
+        ].join(' ')
+    },
     tickformat: {
         valType: 'string',
         dflt: '',
diff --git a/src/plots/cartesian/tick_defaults.js b/src/plots/cartesian/tick_defaults.js
@@ -42,7 +42,18 @@ module.exports = function handleTickDefaults(containerIn, containerOut, coerce,
 
             if(!tickFormat && axType !== 'date') {
                 coerce('showexponent', showAttrDflt);
-                coerce('exponentformat');
+
+                var expBase = coerce('exponentbase'),
+                    expFmtDflt = coerce('exponentformat');
+
+                if (expBase !== 2 && expBase !== 10) expFmtDflt = 'power';
+                if (expBase === 2 && expFmtDflt !== 'SI') expFmtDflt = 'power';
+                if (expBase === 'e'){
+                    containerOut.exponentbase = Math.E;
+                    containerOut.type = 'log';
+                }
+
+                containerOut.exponentformat = expFmtDflt;
             }
         }
 
