v4 colorscale updates (#1647)

* Added 'rebeccapurple' named css color
* Support color lists in colorscale validator
* Support strings of named colors from plotly.colors as colorscale
* Add all legacy plotly.js colorscale definitions to plotly.colors and always coerce color string to colorscale definitions.
* Rename Plotly sequential colorscale to Plotly3 since this was only
the theme default for version 3
* Added sequence colorscale tests
* Change default colorscale for annotated heatmap figure factory to Plasma

packages/python/plotly/_plotly_utils/basevalidators.py

@@ -1234,6 +1234,7 @@ class ColorValidator(BaseValidator):
         "red",
         "rosybrown",
         "royalblue",
+        "rebeccapurple",
         "saddlebrown",
         "salmon",
         "sandybrown",
@@ -1503,86 +1504,118 @@ class ColorscaleValidator(BaseValidator):
         },
     """
 
-    named_colorscales = [
-        "Greys",
-        "YlGnBu",
-        "Greens",
-        "YlOrRd",
-        "Bluered",
-        "RdBu",
-        "Reds",
-        "Blues",
-        "Picnic",
-        "Rainbow",
-        "Portland",
-        "Jet",
-        "Hot",
-        "Blackbody",
-        "Earth",
-        "Electric",
-        "Viridis",
-        "Cividis",
-    ]
-
     def __init__(self, plotly_name, parent_name, **kwargs):
         super(ColorscaleValidator, self).__init__(
             plotly_name=plotly_name, parent_name=parent_name, **kwargs
         )
 
+        # named colorscales initialized on first use
+        self._named_colorscales = None
+
+    @property
+    def named_colorscales(self):
+        if self._named_colorscales is None:
+            import inspect
+            import itertools
+            from plotly import colors
+
+            colorscale_members = itertools.chain(
+                inspect.getmembers(colors.sequential),
+                inspect.getmembers(colors.diverging),
+                inspect.getmembers(colors.cyclical),
+            )
+
+            self._named_colorscales = {
+                c[0].lower(): c[1]
+                for c in colorscale_members
+                if isinstance(c, tuple)
+                and len(c) == 2
+                and isinstance(c[0], str)
+                and isinstance(c[1], list)
+            }
+
+        return self._named_colorscales
+
     def description(self):
+        colorscales_str = "\n".join(
+            textwrap.wrap(
+                repr(sorted(list(self.named_colorscales))),
+                initial_indent=" " * 12,
+                subsequent_indent=" " * 13,
+                break_on_hyphens=False,
+                width=80,
+            )
+        )
+
         desc = """\
     The '{plotly_name}' property is a colorscale and may be
     specified as:
+      - A list of colors that will be spaced evenly to create the colorscale.
+        Many predefined colorscale lists are included in the sequential, diverging,
+        and cyclical modules in the plotly.colors package.
       - A list of 2-element lists where the first element is the
         normalized color level value (starting at 0 and ending at 1), 
         and the second item is a valid color string.
         (e.g. [[0, 'green'], [0.5, 'red'], [1.0, 'rgb(0, 0, 255)']])
       - One of the following named colorscales:
-            ['Greys', 'YlGnBu', 'Greens', 'YlOrRd', 'Bluered', 'RdBu',
-            'Reds', 'Blues', 'Picnic', 'Rainbow', 'Portland', 'Jet',
-            'Hot', 'Blackbody', 'Earth', 'Electric', 'Viridis', 'Cividis']
-        """.format(
-            plotly_name=self.plotly_name
+{colorscales_str}
+""".format(
+            plotly_name=self.plotly_name, colorscales_str=colorscales_str
         )
 
         return desc
 
     def validate_coerce(self, v):
         v_valid = False
 
-        if v is None:
-            # Pass None through
-            pass
         if v is None:
             v_valid = True
         elif isinstance(v, string_types):
-            v_match = [
-                el
-                for el in ColorscaleValidator.named_colorscales
-                if el.lower() == v.lower()
-            ]
-            if v_match:
+            v_lower = v.lower()
+            if v_lower in self.named_colorscales:
+                # Convert to color list
+                v = self.named_colorscales[v_lower]
+
+                # Convert to list of lists colorscale
+                d = len(v) - 1
+                v = [[(1.0 * i) / (1.0 * d), x] for i, x in enumerate(v)]
+
                 v_valid = True
 
         elif is_array(v) and len(v) > 0:
-            invalid_els = [
-                e
-                for e in v
-                if (
-                    not is_array(e)
-                    or len(e) != 2
-                    or not isinstance(e[0], numbers.Number)
-                    or not (0 <= e[0] <= 1)
-                    or not isinstance(e[1], string_types)
-                    or ColorValidator.perform_validate_coerce(e[1]) is None
-                )
-            ]
+            # If firset element is a string, treat as colorsequence
+            if isinstance(v[0], string_types):
+                invalid_els = [
+                    e for e in v if ColorValidator.perform_validate_coerce(e) is None
+                ]
+
+                if len(invalid_els) == 0:
+                    v_valid = True
+
+                    # Convert to list of lists colorscale
+                    d = len(v) - 1
+                    v = [[(1.0 * i) / (1.0 * d), x] for i, x in enumerate(v)]
+            else:
+                invalid_els = [
+                    e
+                    for e in v
+                    if (
+                        not is_array(e)
+                        or len(e) != 2
+                        or not isinstance(e[0], numbers.Number)
+                        or not (0 <= e[0] <= 1)
+                        or not isinstance(e[1], string_types)
+                        or ColorValidator.perform_validate_coerce(e[1]) is None
+                    )
+                ]
 
-            if len(invalid_els) == 0:
-                v_valid = True
+                if len(invalid_els) == 0:
+                    v_valid = True
 
-                # Convert to list of lists
-                v = [[e[0], ColorValidator.perform_validate_coerce(e[1])] for e in v]
+                    # Convert to list of lists
+                    v = [
+                        [e[0], ColorValidator.perform_validate_coerce(e[1])] for e in v
+                    ]
 
         if not v_valid:
             self.raise_invalid_val(v)

packages/python/plotly/plotly/colors/__init__.py → packages/python/plotly/_plotly_utils/colors/__init__.py

@@ -79,7 +79,7 @@
 from numbers import Number
 import six
 
-from plotly import exceptions
+from _plotly_utils import exceptions
 
 
 # Built-in qualitative color sequences and sequential,

packages/python/plotly/plotly/colors/diverging.py → packages/python/plotly/_plotly_utils/colors/diverging.py

@@ -20,6 +20,7 @@
 from .cmocean import balance, delta, curl  # noqa: F401
 from .carto import Armyrose, Fall, Geyser, Temps, Tealrose, Tropic, Earth  # noqa: F401
 
+from .plotlyjs import Picnic, Portland  # noqa: F401
 
 from ._swatches import _swatches
 

packages/python/plotly/_plotly_utils/colors/plotlyjs.py

@@ -0,0 +1,181 @@
+# Copied from
+# https://github.com/plotly/plotly.js/blob/master/src/components/colorscale/scales.js
+_plotlyjs_scales = {
+    "Greys": [[0, "rgb(0,0,0)"], [1, "rgb(255,255,255)"]],
+    "YlGnBu": [
+        [0, "rgb(8,29,88)"],
+        [0.125, "rgb(37,52,148)"],
+        [0.25, "rgb(34,94,168)"],
+        [0.375, "rgb(29,145,192)"],
+        [0.5, "rgb(65,182,196)"],
+        [0.625, "rgb(127,205,187)"],
+        [0.75, "rgb(199,233,180)"],
+        [0.875, "rgb(237,248,217)"],
+        [1, "rgb(255,255,217)"],
+    ],
+    "Greens": [
+        [0, "rgb(0,68,27)"],
+        [0.125, "rgb(0,109,44)"],
+        [0.25, "rgb(35,139,69)"],
+        [0.375, "rgb(65,171,93)"],
+        [0.5, "rgb(116,196,118)"],
+        [0.625, "rgb(161,217,155)"],
+        [0.75, "rgb(199,233,192)"],
+        [0.875, "rgb(229,245,224)"],
+        [1, "rgb(247,252,245)"],
+    ],
+    "YlOrRd": [
+        [0, "rgb(128,0,38)"],
+        [0.125, "rgb(189,0,38)"],
+        [0.25, "rgb(227,26,28)"],
+        [0.375, "rgb(252,78,42)"],
+        [0.5, "rgb(253,141,60)"],
+        [0.625, "rgb(254,178,76)"],
+        [0.75, "rgb(254,217,118)"],
+        [0.875, "rgb(255,237,160)"],
+        [1, "rgb(255,255,204)"],
+    ],
+    "Bluered": [[0, "rgb(0,0,255)"], [1, "rgb(255,0,0)"]],
+    # modified RdBu based on
+    # http:#www.kennethmoreland.com/color-maps/
+    "RdBu": [
+        [0, "rgb(5,10,172)"],
+        [0.35, "rgb(106,137,247)"],
+        [0.5, "rgb(190,190,190)"],
+        [0.6, "rgb(220,170,132)"],
+        [0.7, "rgb(230,145,90)"],
+        [1, "rgb(178,10,28)"],
+    ],
+    # Scale for non-negative numeric values
+    "Reds": [
+        [0, "rgb(220,220,220)"],
+        [0.2, "rgb(245,195,157)"],
+        [0.4, "rgb(245,160,105)"],
+        [1, "rgb(178,10,28)"],
+    ],
+    # Scale for non-positive numeric values
+    "Blues": [
+        [0, "rgb(5,10,172)"],
+        [0.35, "rgb(40,60,190)"],
+        [0.5, "rgb(70,100,245)"],
+        [0.6, "rgb(90,120,245)"],
+        [0.7, "rgb(106,137,247)"],
+        [1, "rgb(220,220,220)"],
+    ],
+    "Picnic": [
+        [0, "rgb(0,0,255)"],
+        [0.1, "rgb(51,153,255)"],
+        [0.2, "rgb(102,204,255)"],
+        [0.3, "rgb(153,204,255)"],
+        [0.4, "rgb(204,204,255)"],
+        [0.5, "rgb(255,255,255)"],
+        [0.6, "rgb(255,204,255)"],
+        [0.7, "rgb(255,153,255)"],
+        [0.8, "rgb(255,102,204)"],
+        [0.9, "rgb(255,102,102)"],
+        [1, "rgb(255,0,0)"],
+    ],
+    "Rainbow": [
+        [0, "rgb(150,0,90)"],
+        [0.125, "rgb(0,0,200)"],
+        [0.25, "rgb(0,25,255)"],
+        [0.375, "rgb(0,152,255)"],
+        [0.5, "rgb(44,255,150)"],
+        [0.625, "rgb(151,255,0)"],
+        [0.75, "rgb(255,234,0)"],
+        [0.875, "rgb(255,111,0)"],
+        [1, "rgb(255,0,0)"],
+    ],
+    "Portland": [
+        [0, "rgb(12,51,131)"],
+        [0.25, "rgb(10,136,186)"],
+        [0.5, "rgb(242,211,56)"],
+        [0.75, "rgb(242,143,56)"],
+        [1, "rgb(217,30,30)"],
+    ],
+    "Jet": [
+        [0, "rgb(0,0,131)"],
+        [0.125, "rgb(0,60,170)"],
+        [0.375, "rgb(5,255,255)"],
+        [0.625, "rgb(255,255,0)"],
+        [0.875, "rgb(250,0,0)"],
+        [1, "rgb(128,0,0)"],
+    ],
+    "Hot": [
+        [0, "rgb(0,0,0)"],
+        [0.3, "rgb(230,0,0)"],
+        [0.6, "rgb(255,210,0)"],
+        [1, "rgb(255,255,255)"],
+    ],
+    "Blackbody": [
+        [0, "rgb(0,0,0)"],
+        [0.2, "rgb(230,0,0)"],
+        [0.4, "rgb(230,210,0)"],
+        [0.7, "rgb(255,255,255)"],
+        [1, "rgb(160,200,255)"],
+    ],
+    "Earth": [
+        [0, "rgb(0,0,130)"],
+        [0.1, "rgb(0,180,180)"],
+        [0.2, "rgb(40,210,40)"],
+        [0.4, "rgb(230,230,50)"],
+        [0.6, "rgb(120,70,20)"],
+        [1, "rgb(255,255,255)"],
+    ],
+    "Electric": [
+        [0, "rgb(0,0,0)"],
+        [0.15, "rgb(30,0,100)"],
+        [0.4, "rgb(120,0,100)"],
+        [0.6, "rgb(160,90,0)"],
+        [0.8, "rgb(230,200,0)"],
+        [1, "rgb(255,250,220)"],
+    ],
+    "Viridis": [
+        [0, "#440154"],
+        [0.06274509803921569, "#48186a"],
+        [0.12549019607843137, "#472d7b"],
+        [0.18823529411764706, "#424086"],
+        [0.25098039215686274, "#3b528b"],
+        [0.3137254901960784, "#33638d"],
+        [0.3764705882352941, "#2c728e"],
+        [0.4392156862745098, "#26828e"],
+        [0.5019607843137255, "#21918c"],
+        [0.5647058823529412, "#1fa088"],
+        [0.6274509803921569, "#28ae80"],
+        [0.6901960784313725, "#3fbc73"],
+        [0.7529411764705882, "#5ec962"],
+        [0.8156862745098039, "#84d44b"],
+        [0.8784313725490196, "#addc30"],
+        [0.9411764705882353, "#d8e219"],
+        [1, "#fde725"],
+    ],
+    "Cividis": [
+        [0.000000, "rgb(0,32,76)"],
+        [0.058824, "rgb(0,42,102)"],
+        [0.117647, "rgb(0,52,110)"],
+        [0.176471, "rgb(39,63,108)"],
+        [0.235294, "rgb(60,74,107)"],
+        [0.294118, "rgb(76,85,107)"],
+        [0.352941, "rgb(91,95,109)"],
+        [0.411765, "rgb(104,106,112)"],
+        [0.470588, "rgb(117,117,117)"],
+        [0.529412, "rgb(131,129,120)"],
+        [0.588235, "rgb(146,140,120)"],
+        [0.647059, "rgb(161,152,118)"],
+        [0.705882, "rgb(176,165,114)"],
+        [0.764706, "rgb(192,177,109)"],
+        [0.823529, "rgb(209,191,102)"],
+        [0.882353, "rgb(225,204,92)"],
+        [0.941176, "rgb(243,219,79)"],
+        [1.000000, "rgb(255,233,69)"],
+    ],
+}
+
+# Create variable named after each scale that contains the sequence of colors only
+for scale_name, scale_pairs in _plotlyjs_scales.items():
+    scale_sequence = [c[1] for c in scale_pairs]
+    exec (
+        "{scale_name} = {scale_sequence}".format(
+            scale_name=scale_name, scale_sequence=scale_sequence
+        )
+    )

packages/python/plotly/plotly/colors/sequential.py → packages/python/plotly/_plotly_utils/colors/sequential.py

@@ -14,7 +14,7 @@ def swatches():
 
 swatches.__doc__ = _swatches.__doc__
 
-Plotly = [
+Plotly3 = [
     "#0508b8",
     "#1910d8",
     "#3c19f0",
@@ -92,6 +92,8 @@ def swatches():
     "#f0f921",
 ]
 
+from .plotlyjs import Blackbody, Bluered, Electric, Hot, Jet, Rainbow  # noqa: F401
+
 from .colorbrewer import (  # noqa: F401
     Blues,
     BuGn,