Add type hints (#146)

* Update colormap.py

* Create test_mypy.yml

* add Mypy requirement

* Update pyproject.toml

* Update element.py

* utilities.py wip

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update branca/utilities.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Restore Div and MacroElement

* Update test_mypy.yml

* Update colormap.py

* Update element.py

* Update utilities.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* error after rebase

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Revert "[pre-commit.ci] auto fixes from pre-commit.com hooks"

This reverts commit e21b6d4.

* another rebase artefact :/

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.github/workflows/test_mypy.yml

@@ -0,0 +1,33 @@
+name: Mypy type hint checks
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  run:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Setup Micromamba env
+      uses: mamba-org/setup-micromamba@v1
+      with:
+        environment-name: TEST
+        create-args: >-
+          python=3
+          --file requirements.txt
+          --file requirements-dev.txt
+
+    - name: Install branca from source
+      shell: bash -l {0}
+      run: |
+        python -m pip install -e . --no-deps --force-reinstall
+
+    - name: Mypy test
+      shell: bash -l {0}
+      run: |
+        mypy branca

branca/colormap.py

@@ -9,51 +9,67 @@
 import json
 import math
 import os
+from typing import Dict, List, Optional, Sequence, Tuple, Union
 
 from jinja2 import Template
 
 from branca.element import ENV, Figure, JavascriptLink, MacroElement
 from branca.utilities import legend_scaler
 
-rootpath = os.path.abspath(os.path.dirname(__file__))
+rootpath: str = os.path.abspath(os.path.dirname(__file__))
 
 with open(os.path.join(rootpath, "_cnames.json")) as f:
-    _cnames = json.loads(f.read())
+    _cnames: Dict[str, str] = json.loads(f.read())
 
 with open(os.path.join(rootpath, "_schemes.json")) as f:
-    _schemes = json.loads(f.read())
+    _schemes: Dict[str, List[str]] = json.loads(f.read())
 
 
-def _is_hex(x):
+TypeRGBInts = Tuple[int, int, int]
+TypeRGBFloats = Tuple[float, float, float]
+TypeRGBAInts = Tuple[int, int, int, int]
+TypeRGBAFloats = Tuple[float, float, float, float]
+TypeAnyColorType = Union[TypeRGBInts, TypeRGBFloats, TypeRGBAInts, TypeRGBAFloats, str]
+
+
+def _is_hex(x: str) -> bool:
     return x.startswith("#") and len(x) == 7
 
 
-def _parse_hex(color_code):
+def _parse_hex(color_code: str) -> TypeRGBAFloats:
     return (
-        int(color_code[1:3], 16),
-        int(color_code[3:5], 16),
-        int(color_code[5:7], 16),
+        _color_int_to_float(int(color_code[1:3], 16)),
+        _color_int_to_float(int(color_code[3:5], 16)),
+        _color_int_to_float(int(color_code[5:7], 16)),
+        1.0,
     )
 
 
-def _parse_color(x):
+def _color_int_to_float(x: int) -> float:
+    """Convert an integer between 0 and 255 to a float between 0. and 1.0"""
+    return x / 255.0
+
+
+def _color_float_to_int(x: float) -> int:
+    """Convert a float between 0. and 1.0 to an integer between 0 and 255"""
+    return int(x * 255.9999)
+
+
+def _parse_color(x: Union[tuple, list, str]) -> TypeRGBAFloats:
     if isinstance(x, (tuple, list)):
-        color_tuple = tuple(x)[:4]
-    elif isinstance(x, (str, bytes)) and _is_hex(x):
-        color_tuple = _parse_hex(x)
-    elif isinstance(x, (str, bytes)):
+        return tuple(tuple(x) + (1.0,))[:4]  # type: ignore
+    elif isinstance(x, str) and _is_hex(x):
+        return _parse_hex(x)
+    elif isinstance(x, str):
         cname = _cnames.get(x.lower(), None)
         if cname is None:
             raise ValueError(f"Unknown color {cname!r}.")
-        color_tuple = _parse_hex(cname)
+        return _parse_hex(cname)
     else:
         raise ValueError(f"Unrecognized color code {x!r}")
-    if max(color_tuple) > 1.0:
-        color_tuple = tuple(u / 255.0 for u in color_tuple)
-    return tuple(map(float, (color_tuple + (1.0,))[:4]))
 
 
-def _base(x):
+def _base(x: float) -> float:
     if x > 0:
         base = pow(10, math.floor(math.log10(x)))
         return round(x / base) * base
@@ -78,15 +94,15 @@ class ColorMap(MacroElement):
         Maximum number of legend tick labels
     """
 
-    _template = ENV.get_template("color_scale.js")
+    _template: Template = ENV.get_template("color_scale.js")
 
     def __init__(
         self,
-        vmin=0.0,
-        vmax=1.0,
-        caption="",
-        text_color="black",
-        max_labels=10,
+        vmin: float = 0.0,
+        vmax: float = 1.0,
+        caption: str = "",
+        text_color: str = "black",
+        max_labels: int = 10,
     ):
         super().__init__()
         self._name = "ColorMap"
@@ -95,9 +111,9 @@ def __init__(
         self.vmax = vmax
         self.caption = caption
         self.text_color = text_color
-        self.index = [vmin, vmax]
+        self.index: List[float] = [vmin, vmax]
         self.max_labels = max_labels
-        self.tick_labels = None
+        self.tick_labels: Optional[Sequence[Union[float, str]]] = None
 
         self.width = 450
         self.height = 40
@@ -127,7 +143,7 @@ def render(self, **kwargs):
             name="d3",
         )  # noqa
 
-    def rgba_floats_tuple(self, x):
+    def rgba_floats_tuple(self, x: float) -> TypeRGBAFloats:
         """
         This class has to be implemented for each class inheriting from
         Colormap. This has to be a function of the form float ->
@@ -137,37 +153,37 @@ def rgba_floats_tuple(self, x):
         """
         raise NotImplementedError
 
-    def rgba_bytes_tuple(self, x):
+    def rgba_bytes_tuple(self, x: float) -> TypeRGBAInts:
         """Provides the color corresponding to value `x` in the
         form of a tuple (R,G,B,A) with int values between 0 and 255.
         """
-        return tuple(int(u * 255.9999) for u in self.rgba_floats_tuple(x))
+        return tuple(_color_float_to_int(u) for u in self.rgba_floats_tuple(x))  # type: ignore
 
-    def rgb_bytes_tuple(self, x):
+    def rgb_bytes_tuple(self, x: float) -> TypeRGBInts:
         """Provides the color corresponding to value `x` in the
         form of a tuple (R,G,B) with int values between 0 and 255.
         """
         return self.rgba_bytes_tuple(x)[:3]
 
-    def rgb_hex_str(self, x):
+    def rgb_hex_str(self, x: float) -> str:
         """Provides the color corresponding to value `x` in the
         form of a string of hexadecimal values "#RRGGBB".
         """
         return "#%02x%02x%02x" % self.rgb_bytes_tuple(x)
 
-    def rgba_hex_str(self, x):
+    def rgba_hex_str(self, x: float) -> str:
         """Provides the color corresponding to value `x` in the
         form of a string of hexadecimal values "#RRGGBBAA".
         """
         return "#%02x%02x%02x%02x" % self.rgba_bytes_tuple(x)
 
-    def __call__(self, x):
+    def __call__(self, x: float) -> str:
         """Provides the color corresponding to value `x` in the
         form of a string of hexadecimal values "#RRGGBBAA".
         """
         return self.rgba_hex_str(x)
 
-    def _repr_html_(self):
+    def _repr_html_(self) -> str:
         """Display the colormap in a Jupyter Notebook.
 
         Does not support all the class arguments.
@@ -264,14 +280,14 @@ class LinearColormap(ColorMap):
 
     def __init__(
         self,
-        colors,
-        index=None,
-        vmin=0.0,
-        vmax=1.0,
-        caption="",
-        text_color="black",
-        max_labels=10,
-        tick_labels=None,
+        colors: Sequence[TypeAnyColorType],
+        index: Optional[Sequence[float]] = None,
+        vmin: float = 0.0,
+        vmax: float = 1.0,
+        caption: str = "",
+        text_color: str = "black",
+        max_labels: int = 10,
+        tick_labels: Optional[Sequence[float]] = None,
     ):
         super().__init__(
             vmin=vmin,
@@ -280,7 +296,7 @@ def __init__(
             text_color=text_color,
             max_labels=max_labels,
         )
-        self.tick_labels = tick_labels
+        self.tick_labels: Optional[Sequence[float]] = tick_labels
 
         n = len(colors)
         if n < 2:
@@ -289,9 +305,9 @@ def __init__(
             self.index = [vmin + (vmax - vmin) * i * 1.0 / (n - 1) for i in range(n)]
         else:
             self.index = list(index)
-        self.colors = [_parse_color(x) for x in colors]
+        self.colors: List[TypeRGBAFloats] = [_parse_color(x) for x in colors]
 
-    def rgba_floats_tuple(self, x):
+    def rgba_floats_tuple(self, x: float) -> TypeRGBAFloats:
         """Provides the color corresponding to value `x` in the
         form of a tuple (R,G,B,A) with float values between 0. and 1.
         """
@@ -308,20 +324,20 @@ def rgba_floats_tuple(self, x):
         else:
             raise ValueError("Thresholds are not sorted.")
 
-        return tuple(
+        return tuple(  # type: ignore
             (1.0 - p) * self.colors[i - 1][j] + p * self.colors[i][j] for j in range(4)
         )
 
     def to_step(
         self,
-        n=None,
-        index=None,
-        data=None,
-        method=None,
-        quantiles=None,
-        round_method=None,
-        max_labels=10,
-    ):
+        n: Optional[int] = None,
+        index: Optional[Sequence[float]] = None,
+        data: Optional[Sequence[float]] = None,
+        method: str = "linear",
+        quantiles: Optional[Sequence[float]] = None,
+        round_method: Optional[str] = None,
+        max_labels: int = 10,
+    ) -> "StepColormap":
         """Splits the LinearColormap into a StepColormap.
 
         Parameters
@@ -382,11 +398,7 @@ def to_step(
                 max_ = max(data)
                 min_ = min(data)
                 scaled_cm = self.scale(vmin=min_, vmax=max_)
-                method = (
-                    "quantiles"
-                    if quantiles is not None
-                    else method if method is not None else "linear"
-                )
+                method = "quantiles" if quantiles is not None else method
                 if method.lower().startswith("lin"):
                     if n is None:
                         raise ValueError(msg)
@@ -454,7 +466,12 @@ def to_step(
             tick_labels=self.tick_labels,
         )
 
-    def scale(self, vmin=0.0, vmax=1.0, max_labels=10):
+    def scale(
+        self,
+        vmin: float = 0.0,
+        vmax: float = 1.0,
+        max_labels: int = 10,
+    ) -> "LinearColormap":
         """Transforms the colorscale so that the minimal and maximal values
         fit the given parameters.
         """
@@ -510,14 +527,14 @@ class StepColormap(ColorMap):
 
     def __init__(
         self,
-        colors,
-        index=None,
-        vmin=0.0,
-        vmax=1.0,
-        caption="",
-        text_color="black",
-        max_labels=10,
-        tick_labels=None,
+        colors: Sequence[TypeAnyColorType],
+        index: Optional[Sequence[float]] = None,
+        vmin: float = 0.0,
+        vmax: float = 1.0,
+        caption: str = "",
+        text_color: str = "black",
+        max_labels: int = 10,
+        tick_labels: Optional[Sequence[float]] = None,
     ):
         super().__init__(
             vmin=vmin,
@@ -535,9 +552,9 @@ def __init__(
             self.index = [vmin + (vmax - vmin) * i * 1.0 / n for i in range(n + 1)]
         else:
             self.index = list(index)
-        self.colors = [_parse_color(x) for x in colors]
+        self.colors: List[TypeRGBAFloats] = [_parse_color(x) for x in colors]
 
-    def rgba_floats_tuple(self, x):
+    def rgba_floats_tuple(self, x: float) -> TypeRGBAFloats:
         """
         Provides the color corresponding to value `x` in the
         form of a tuple (R,G,B,A) with float values between 0. and 1.
@@ -549,9 +566,13 @@ def rgba_floats_tuple(self, x):
             return self.colors[-1]
 
         i = len([u for u in self.index if u <= x])  # 0 < i < n.
-        return tuple(self.colors[i - 1])
+        return self.colors[i - 1]
 
-    def to_linear(self, index=None, max_labels=10):
+    def to_linear(
+        self,
+        index: Optional[Sequence[float]] = None,
+        max_labels: int = 10,
+    ) -> LinearColormap:
         """
         Transforms the StepColormap into a LinearColormap.
 
@@ -584,7 +605,12 @@ def to_linear(self, index=None, max_labels=10):
             max_labels=max_labels,
         )
 
-    def scale(self, vmin=0.0, vmax=1.0, max_labels=10):
+    def scale(
+        self,
+        vmin: float = 0.0,
+        vmax: float = 1.0,
+        max_labels: int = 10,
+    ) -> "StepColormap":
         """Transforms the colorscale so that the minimal and maximal values
         fit the given parameters.
         """
@@ -611,7 +637,7 @@ def __init__(self):
         for key, val in _schemes.items():
             setattr(self, key, LinearColormap(val))
 
-    def _repr_html_(self):
+    def _repr_html_(self) -> str:
         return Template(
             """
         <table>
@@ -634,7 +660,7 @@ def __init__(self):
         for key, val in _schemes.items():
             setattr(self, key, StepColormap(val))
 
-    def _repr_html_(self):
+    def _repr_html_(self) -> str:
         return Template(
             """
         <table>