documentation updates

Author: alexcjohnson

src/plots/cartesian/axes.js

@@ -92,7 +92,10 @@ axes.coerceRef = function(containerIn, containerOut, gd, attr, dflt, extraOption
  *
  * Also cleans the values, since the attribute definition itself has to say
  * valType: 'any' to handle date axes. This allows us to accept:
- * - for category axes: category names, and convert them here into serial numbers
+ * - for category axes: category names, and convert them here into serial numbers.
+ *   Note that this will NOT work for axis range endpoints, because we don't know
+ *   the category list yet (it's set by ax.makeCalcdata during calc)
+ *   but it works for component (note, shape, images) positions.
  * - for date axes: JS Dates or milliseconds, and convert to date strings
  * - for other types: coerce them to numbers
  */

src/plots/cartesian/layout_attributes.js

@@ -329,23 +329,29 @@ module.exports = {
         dflt: '',
         role: 'style',
         description: [
-            'Sets the tick label formatting rule using the',
-            'python/d3 number formatting language.',
-            'See https://github.com/mbostock/d3/wiki/Formatting#numbers',
-            'or https://docs.python.org/release/3.1.3/library/string.html#formatspec',
-            'for more info.'
+            'Sets the tick label formatting rule using d3 formatting mini-languages',
+            'which are very similar to those in Python. For numbers, see:',
+            'https://github.com/d3/d3-format/blob/master/README.md#locale_format',
+            'And for dates see:',
+            'https://github.com/d3/d3-time-format/blob/master/README.md#locale_format',
+            'We add one item to d3\'s date formatter: *%{n}f* for fractional seconds',
+            'with n digits. For example, *2016-10-13 09:15:23.456* with tickformat',
+            '*%H~%M~%S.%2f* would display *09~15~23.46*'
         ].join(' ')
     },
     hoverformat: {
         valType: 'string',
         dflt: '',
         role: 'style',
         description: [
-            'Sets the hover text formatting rule for data values on this axis,',
-            'using the python/d3 number formatting language.',
-            'See https://github.com/mbostock/d3/wiki/Formatting#numbers',
-            'or https://docs.python.org/release/3.1.3/library/string.html#formatspec',
-            'for more info.'
+            'Sets the hover text formatting rule using d3 formatting mini-languages',
+            'which are very similar to those in Python. For numbers, see:',
+            'https://github.com/d3/d3-format/blob/master/README.md#locale_format',
+            'And for dates see:',
+            'https://github.com/d3/d3-time-format/blob/master/README.md#locale_format',
+            'We add one item to d3\'s date formatter: *%{n}f* for fractional seconds',
+            'with n digits. For example, *2016-10-13 09:15:23.456* with tickformat',
+            '*%H~%M~%S.%2f* would display *09~15~23.46*'
         ].join(' ')
     },
     // lines and grids