Better automatic y-labelling.

lib/morris.grid.coffee

@@ -161,31 +161,14 @@ class Morris.Grid extends Morris.EventEmitter
       @ymax += 1
 
     if @options.axes is true or @options.grid is true
-      # calculate grid placement
-      span = @ymax - @ymin
-      ymag = Math.floor(Math.log(span) / Math.log(10))
-      unit = Math.pow(10, ymag)
-
-      # calculate initial grid min and max values
-      gmin = Math.round(@ymin / unit) * unit
-      gmax = Math.round(@ymax / unit) * unit
-      step = (gmax - gmin) / (@options.numLines - 1)
-
-      # ensure zero is plotted where the range includes zero
-      if gmin < 0 and gmax > 0
-        gmin = Math.round(@ymin / step) * step
-        gmax = Math.round(@ymax / step) * step
-
-      # special case for decimal numbers
-      if step < 1
-        smag = Math.floor(Math.log(step) / Math.log(10))
-        @grid = for y in [gmin..gmax] by step
-          parseFloat(y.toFixed(1 - smag))
+      if @options.ymax == @defaults.ymax and @options.ymin == @defaults.ymin
+        # calculate 'magic' grid placement
+        @grid = @autoGridLines(@ymin, @ymax, @options.numLines)
+        @ymin = Math.min(@ymin, @grid[0])
+        @ymax = Math.max(@ymax, @grid[@grid.length - 1])
       else
-        @grid = (y for y in [gmin..gmax] by step)
-
-      @ymin = gmin
-      @ymax = gmax
+        step = (@ymax - @ymin) / (@options.numLines - 1)
+        @grid = (y for y in [@ymin..@ymax] by step)
 
     @dirty = true
     @redraw() if redraw
@@ -205,6 +188,33 @@ class Morris.Grid extends Morris.EventEmitter
     else
       boundaryOption
 
+  autoGridLines: (ymin, ymax, nlines) ->
+    span = ymax - ymin
+    ymag = Math.floor(Math.log(span) / Math.log(10))
+    unit = Math.pow(10, ymag)
+
+    # calculate initial grid min and max values
+    gmin = Math.floor(ymin / unit) * unit
+    gmax = Math.ceil(ymax / unit) * unit
+    step = (gmax - gmin) / (nlines - 1)
+    if unit == 1 and step > 1 and Math.ceil(step) != step
+      step = Math.ceil(step)
+      gmax = gmin + step * (nlines - 1)
+
+    # ensure zero is plotted where the range includes zero
+    if gmin < 0 and gmax > 0
+      gmin = Math.floor(ymin / step) * step
+      gmax = Math.ceil(ymax / step) * step
+
+    # special case for decimal numbers
+    if step < 1
+      smag = Math.floor(Math.log(step) / Math.log(10))
+      grid = for y in [gmin..gmax] by step
+        parseFloat(y.toFixed(1 - smag))
+    else
+      grid = (y for y in [gmin..gmax] by step)
+    grid
+
   _calc: ->
     w = @el.width()
     h = @el.height()

morris.js

@@ -138,7 +138,7 @@
     };
 
     Grid.prototype.setData = function(data, redraw) {
-      var e, gmax, gmin, idx, index, maxGoal, minGoal, ret, row, smag, span, step, total, unit, y, ykey, ymag, ymax, ymin, yval;
+      var e, idx, index, maxGoal, minGoal, ret, row, step, total, y, ykey, ymax, ymin, yval;
       if (redraw == null) {
         redraw = true;
       }
@@ -248,38 +248,21 @@
         this.ymax += 1;
       }
       if (this.options.axes === true || this.options.grid === true) {
-        span = this.ymax - this.ymin;
-        ymag = Math.floor(Math.log(span) / Math.log(10));
-        unit = Math.pow(10, ymag);
-        gmin = Math.round(this.ymin / unit) * unit;
-        gmax = Math.round(this.ymax / unit) * unit;
-        step = (gmax - gmin) / (this.options.numLines - 1);
-        if (gmin < 0 && gmax > 0) {
-          gmin = Math.round(this.ymin / step) * step;
-          gmax = Math.round(this.ymax / step) * step;
-        }
-        if (step < 1) {
-          smag = Math.floor(Math.log(step) / Math.log(10));
-          this.grid = (function() {
-            var _i, _results;
-            _results = [];
-            for (y = _i = gmin; gmin <= gmax ? _i <= gmax : _i >= gmax; y = _i += step) {
-              _results.push(parseFloat(y.toFixed(1 - smag)));
-            }
-            return _results;
-          })();
+        if (this.options.ymax === this.defaults.ymax && this.options.ymin === this.defaults.ymin) {
+          this.grid = this.autoGridLines(this.ymin, this.ymax, this.options.numLines);
+          this.ymin = Math.min(this.ymin, this.grid[0]);
+          this.ymax = Math.max(this.ymax, this.grid[this.grid.length - 1]);
         } else {
+          step = (this.ymax - this.ymin) / (this.options.numLines - 1);
           this.grid = (function() {
-            var _i, _results;
+            var _i, _ref, _ref1, _results;
             _results = [];
-            for (y = _i = gmin; gmin <= gmax ? _i <= gmax : _i >= gmax; y = _i += step) {
+            for (y = _i = _ref = this.ymin, _ref1 = this.ymax; _ref <= _ref1 ? _i <= _ref1 : _i >= _ref1; y = _i += step) {
               _results.push(y);
             }
             return _results;
-          })();
+          }).call(this);
         }
-        this.ymin = gmin;
-        this.ymax = gmax;
       }
       this.dirty = true;
       if (redraw) {
@@ -313,6 +296,45 @@
       }
     };
 
+    Grid.prototype.autoGridLines = function(ymin, ymax, nlines) {
+      var gmax, gmin, grid, smag, span, step, unit, y, ymag;
+      span = ymax - ymin;
+      ymag = Math.floor(Math.log(span) / Math.log(10));
+      unit = Math.pow(10, ymag);
+      gmin = Math.floor(ymin / unit) * unit;
+      gmax = Math.ceil(ymax / unit) * unit;
+      step = (gmax - gmin) / (nlines - 1);
+      if (unit === 1 && step > 1 && Math.ceil(step) !== step) {
+        step = Math.ceil(step);
+        gmax = gmin + step * (nlines - 1);
+      }
+      if (gmin < 0 && gmax > 0) {
+        gmin = Math.floor(ymin / step) * step;
+        gmax = Math.ceil(ymax / step) * step;
+      }
+      if (step < 1) {
+        smag = Math.floor(Math.log(step) / Math.log(10));
+        grid = (function() {
+          var _i, _results;
+          _results = [];
+          for (y = _i = gmin; gmin <= gmax ? _i <= gmax : _i >= gmax; y = _i += step) {
+            _results.push(parseFloat(y.toFixed(1 - smag)));
+          }
+          return _results;
+        })();
+      } else {
+        grid = (function() {
+          var _i, _results;
+          _results = [];
+          for (y = _i = gmin; gmin <= gmax ? _i <= gmax : _i >= gmax; y = _i += step) {
+            _results.push(y);
+          }
+          return _results;
+        })();
+      }
+      return grid;
+    };
+
     Grid.prototype._calc = function() {
       var h, maxYLabelWidth, w;
       w = this.el.width();

spec/lib/grid/auto_grid_lines_spec.coffee

@@ -0,0 +1,25 @@
+describe 'Morris.Grid#autoGridLines', ->
+
+  beforeEach ->
+    @subject = Morris.Grid.prototype.autoGridLines
+
+  it 'should draw at fixed intervals', ->
+    @subject(0, 4, 5).should.deep.equal [0, 1, 2, 3, 4]
+    @subject(0, 400, 5).should.deep.equal [0, 100, 200, 300, 400]
+
+  it 'should pick intervals that show significant numbers', ->
+    @subject(102, 499, 5).should.deep.equal [100, 200, 300, 400, 500]
+
+  it 'should draw zero when it falls within [ymin..ymax]', ->
+    @subject(-100, 300, 5).should.deep.equal [-100, 0, 100, 200, 300]
+    @subject(-50, 350, 5).should.deep.equal [-125, 0, 125, 250, 375]
+    @subject(-400, 400, 5).should.deep.equal [-400, -200, 0, 200, 400]
+    @subject(100, 500, 5).should.deep.equal [100, 200, 300, 400, 500]
+    @subject(-500, -100, 5).should.deep.equal [-500, -400, -300, -200, -100]
+
+  it 'should generate decimal labels to 2 significant figures', ->
+    @subject(0, 1, 5).should.deep.equal [0, 0.25, 0.5, 0.75, 1]
+    @subject(0.1, 0.5, 5).should.deep.equal [0.1, 0.2, 0.3, 0.4, 0.5]
+
+  it 'should use integer intervals for intervals larger than 1', ->
+    @subject(0, 9, 5).should.deep.equal [0, 3, 6, 9, 12]

spec/lib/grid/interval_spec.coffee

@@ -1,42 +0,0 @@
-gridLines = (ymin, ymax, nlines = 5) ->
-  interval = ymax - ymin
-  omag = Math.floor(Math.log(interval) / Math.log(10))
-  unit = Math.pow(10, omag)
-
-  ymin1 = Math.round(ymin / unit) * unit
-  ymax1 = Math.round(ymax / unit) * unit
-  step = (ymax1 - ymin1) / (nlines - 1)
-
-  # ensure zero is plotted where the range includes zero
-  if ymin1 < 0 and ymax1 > 0
-    ymin1 = Math.round(ymin / step) * step
-    ymax1 = Math.round(ymax / step) * step
-
-  # small numbers
-  if step < 1
-    smag = Math.floor(Math.log(step) / Math.log(10))
-    (parseFloat(y.toFixed(1 - smag)) for y in [ymin1..ymax1] by step)
-  else
-    (y for y in [ymin1..ymax1] by step)
-
-describe 'Morris.Grid#gridLines', ->
-
-  it 'should draw at fixed intervals', ->
-    gridLines(0, 4).should.deep.equal [0, 1, 2, 3, 4]
-    gridLines(0, 400).should.deep.equal [0, 100, 200, 300, 400]
-
-  it 'should pick intervals that show significant numbers', ->
-    gridLines(98, 502).should.deep.equal [100, 200, 300, 400, 500]
-    gridLines(98, 302).should.deep.equal [100, 150, 200, 250, 300]
-    gridLines(98, 202).should.deep.equal [100, 125, 150, 175, 200]
-
-  it 'should draw zero when it falls within [ymin..ymax]', ->
-    gridLines(-100, 300).should.deep.equal [-100, 0, 100, 200, 300]
-    gridLines(-50, 350).should.deep.equal [0, 100, 200, 300, 400]
-    gridLines(-500, 300).should.deep.equal [-400, -200, 0, 200, 400]
-    gridLines(100, 500).should.deep.equal [100, 200, 300, 400, 500]
-    gridLines(-500, -100).should.deep.equal [-500, -400, -300, -200, -100]
-
-  it 'should generate decimal labels to 2 signigicant figures', ->
-    gridLines(0, 1).should.deep.equal [0, 0.25, 0.5, 0.75, 1]
-    gridLines(0.1, 0.5).should.deep.equal [0.1, 0.2, 0.3, 0.4, 0.5]

spec/lib/grid/set_data_spec.coffee

@@ -197,3 +197,12 @@ describe 'Morris.Grid#setData', ->
     line.data.length.should.equal 0
     line.setData([{x: 2, y: '12'}, {x: 1, y: '13.5'}, {x: 4, y: '14'}, {x: 3, y: '16'}])
     line.data.length.should.equal 4
+
+  it 'should automatically choose significant numbers for y-labels', ->
+    line = Morris.Line
+      element: 'graph',
+      data: [{x: 1, y: 0}, {x: 2, y: 3600}]
+      xkey: 'x'
+      ykeys: ['y']
+      labels: ['y']
+    line.grid.should == [0, 1000, 2000, 3000, 4000]