Add "tickpadding" property to control distance between ticks when tickmode is auto

src/components/colorbar/defaults.js

@@ -13,6 +13,7 @@ var Lib = require('../../lib');
 var handleTickValueDefaults = require('../../plots/cartesian/tick_value_defaults');
 var handleTickMarkDefaults = require('../../plots/cartesian/tick_mark_defaults');
 var handleTickLabelDefaults = require('../../plots/cartesian/tick_label_defaults');
+var cartesianAxesAttrs = require('../../plots/cartesian/layout_attributes');
 
 var attributes = require('./attributes');
 
@@ -21,8 +22,11 @@ module.exports = function colorbarDefaults(containerIn, containerOut, layout) {
     var colorbarOut = containerOut.colorbar = {},
         colorbarIn = containerIn.colorbar || {};
 
+    //colorbar doesn't currently implement tickpadding property, but it is a required attribute of a cartesian axis
+    var cartesianAttributes = Lib.extendFlat({}, attributes, { tickpadding: cartesianAxesAttrs.tickpadding });
+
     function coerce(attr, dflt) {
-        return Lib.coerce(colorbarIn, colorbarOut, attributes, attr, dflt);
+        return Lib.coerce(colorbarIn, colorbarOut, cartesianAttributes, attr, dflt);
     }
 
     var thicknessmode = coerce('thicknessmode');

src/components/colorbar/draw.js

@@ -156,6 +156,7 @@ module.exports = function draw(gd, id) {
                 showticklabels: opts.showticklabels,
                 tickfont: opts.tickfont,
                 tickangle: opts.tickangle,
+                tickpadding: opts.tickpadding,
                 tickformat: opts.tickformat,
                 exponentformat: opts.exponentformat,
                 separatethousands: opts.separatethousands,

src/plots/cartesian/axes.js

@@ -535,10 +535,13 @@ axes.calcTicks = function calcTicks(ax) {
         if(!nt) {
             if(ax.type === 'category') {
                 minPx = ax.tickfont ? (ax.tickfont.size || 12) * 1.2 : 15;
+                minPx += ax.tickpadding;
                 nt = ax._length / minPx;
             }
             else {
                 minPx = ax._id.charAt(0) === 'y' ? 40 : 80;
+                minPx += ax.tickpadding;
+
                 nt = Lib.constrain(ax._length / minPx, 4, 9) + 1;
             }
         }

src/plots/cartesian/layout_attributes.js

@@ -251,6 +251,15 @@ module.exports = {
             'vertically.'
         ].join(' ')
     },
+    tickpadding: {
+        valType: 'number',
+        dflt: 0,
+        role: 'style',
+        description: [
+            'Sets extra padding between ticks.',
+            'This can be used to control the number of ticks displayed without explicitly specifying nticks.'
+        ].join(' ')
+    },
     tickprefix: {
         valType: 'string',
         dflt: '',

src/plots/cartesian/tick_value_defaults.js

@@ -10,7 +10,7 @@
 'use strict';
 
 var isNumeric = require('fast-isnumeric');
-
+var layoutAttributes = require('./layout_attributes');
 
 module.exports = function handleTickValueDefaults(containerIn, containerOut, coerce, axType) {
     var tickmodeDefault = 'auto';
@@ -26,7 +26,17 @@ module.exports = function handleTickValueDefaults(containerIn, containerOut, coe
     }
     var tickmode = coerce('tickmode', tickmodeDefault);
 
-    if(tickmode === 'auto') coerce('nticks');
+    if(tickmode === 'auto') {
+        var nticks = coerce('nticks');
+
+        //Only use tickpadding if tickmode is 'auto' and the user doesn't specify nticks
+        if(nticks === layoutAttributes.nticks.dflt) {
+            coerce('tickpadding');
+        }
+        else {
+            containerOut.tickpadding = layoutAttributes.tickpadding.dflt;
+        }
+    }
     else if(tickmode === 'linear') {
         coerce('tick0');
         coerce('dtick');

src/plots/gl3d/layout/axis_defaults.js

@@ -15,6 +15,7 @@ var Lib = require('../../../lib');
 
 var layoutAttributes = require('./axis_attributes');
 var handleAxisDefaults = require('../../cartesian/axis_defaults');
+var cartesianAxesAttrs = require('../../cartesian/layout_attributes');
 
 var axesNames = ['xaxis', 'yaxis', 'zaxis'];
 var noop = function() {};
@@ -26,8 +27,11 @@ var gridLightness = 100 * (204 - 0x44) / (255 - 0x44);
 module.exports = function supplyLayoutDefaults(layoutIn, layoutOut, options) {
     var containerIn, containerOut;
 
+    //gl3d doesn't currently implement tickpadding property, but it is a required attribute of a cartesian axis
+    var cartesianLayoutAttributes = Lib.extendFlat({}, layoutAttributes, { tickpadding: cartesianAxesAttrs.tickpadding });
+
     function coerce(attr, dflt) {
-        return Lib.coerce(containerIn, containerOut, layoutAttributes, attr, dflt);
+        return Lib.coerce(containerIn, containerOut, cartesianLayoutAttributes, attr, dflt);
     }
 
     for(var j = 0; j < axesNames.length; j++) {

test/image/mocks/axes-tickpadding.json

@@ -0,0 +1,103 @@
+{
+    "data": [
+        {
+            "x": [
+                0,
+                1,
+                2,
+                3,
+                4,
+                5,
+                6,
+                7,
+                8,
+                9,
+                10,
+                11,
+                12,
+                13,
+                14,
+                15,
+                16,
+                17,
+                18,
+                19,
+                20,
+                21,
+                22,
+                23,
+                24,
+                25,
+                26,
+                27,
+                28,
+                29,
+                30,
+                31,
+                32,
+                33,
+                34,
+                35,
+                36,
+                37,
+                38,
+                39
+            ],
+            "y": [
+                0,
+                1,
+                2,
+                3,
+                4,
+                5,
+                6,
+                7,
+                8,
+                9,
+                10,
+                11,
+                12,
+                13,
+                14,
+                15,
+                16,
+                17,
+                18,
+                19,
+                20,
+                21,
+                22,
+                23,
+                24,
+                25,
+                26,
+                27,
+                28,
+                29,
+                30,
+                31,
+                32,
+                33,
+                34,
+                35,
+                36,
+                37,
+                38,
+                39
+            ],
+            "type": "scatter"
+        }
+    ],
+    "layout": {
+        "xaxis": {
+            "type": "category",
+            "tickmode": "auto",
+            "tickpadding": 15
+        },
+        "yaxis": {
+            "type": "category",
+            "tickmode": "auto",
+            "tickpadding": 20
+        }
+    }
+}

test/jasmine/tests/axes_test.js

@@ -556,6 +556,7 @@ describe('Test axes', function() {
             expect(yaxis.showticklabels).toBe(true);
             expect(yaxis.tickfont).toEqual({ family: '"Open Sans", verdana, arial, sans-serif', size: 12, color: '#444' });
             expect(yaxis.tickangle).toBe('auto');
+            expect(yaxis.tickpadding).toBe(0);
         });
 
         it('should use valid inputs', function() {
@@ -566,7 +567,9 @@ describe('Test axes', function() {
                     tickcolor: '#F00',
                     showticklabels: true,
                     tickfont: { family: 'Garamond', size: 72, color: '#0FF' },
-                    tickangle: -20
+                    tickangle: -20,
+                    tickmode: 'auto',
+                    tickpadding: 15
                 }
             };
 
@@ -580,6 +583,7 @@ describe('Test axes', function() {
             expect(yaxis.showticklabels).toBe(true);
             expect(yaxis.tickfont).toEqual({ family: 'Garamond', size: 72, color: '#0FF' });
             expect(yaxis.tickangle).toBe(-20);
+            expect(yaxis.tickpadding).toBe(15);
         });
 
         it('should conditionally coerce based on showticklabels', function() {
@@ -595,6 +599,21 @@ describe('Test axes', function() {
             var yaxis = gd._fullLayout.yaxis;
             expect(yaxis.tickangle).toBeUndefined();
         });
+
+        it('should conditionally coerce tickpadding if nticks is set', function() {
+            var layout = {
+                yaxis: {
+                    tickmode: 'auto',
+                    nticks: 5,
+                    tickpadding: 20
+                }
+            };
+
+            PlotlyInternal.plot(gd, data, layout);
+
+            var yaxis = gd._fullLayout.yaxis;
+            expect(yaxis.tickpadding).toBe(0);
+        });
     });
 
     describe('handleTickValueDefaults', function() {