add gridstyle

Author: ahuang11

doc/ref/plotting_options/grid_legend.ipynb

@@ -69,6 +69,76 @@
     "plot1 + plot2"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "1cee746c",
+   "metadata": {},
+   "source": [
+    "Use `grid=\"x\"` to draw vertical lines or `grid=\"y\"` to draw horizontal lines only."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "91cb84f5",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import hvplot.pandas  # noqa\n",
+    "import hvsampledata\n",
+    "\n",
+    "df = hvsampledata.stocks(\"pandas\", engine_kwargs={\"index_col\" : \"date\"})\n",
+    "\n",
+    "plot1 = df.hvplot(group_label=\"Company\", grid=\"x\", width=400, title=\"grid='x'\")\n",
+    "plot2 = df.hvplot(group_label=\"Company\", grid=\"y\", width=400, title=\"grid='y'\")\n",
+    "\n",
+    "plot1 + plot2"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "d426fda0",
+   "metadata": {},
+   "source": [
+    "Additionally, `'dashed'`, `'dotted'`, `'dotdash'`, or `'dashdot'` can be suffixed to the `grid` string to achieve a non-solid line."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "7b76bff4",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import hvplot.pandas  # noqa\n",
+    "import hvsampledata\n",
+    "\n",
+    "df = hvsampledata.stocks(\"pandas\", engine_kwargs={\"index_col\" : \"date\"})\n",
+    "\n",
+    "solid_plot = df.hvplot(group_label=\"Company\", grid=\"x\", width=400, title=\"grid='x'\")\n",
+    "for line_style in [\"dashed\", \"dotted\", \"dotdash\", \"dashdot\"]:\n",
+    "    non_solid_plot = df.hvplot(group_label=\"Company\", grid=f\"x_{line_style}\", width=400, title=f\"grid='x{line_style}'\")\n",
+    "    solid_plot += non_solid_plot"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "0cbb3df0",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import hvplot.pandas  # noqa\n",
+    "import hvsampledata\n",
+    "\n",
+    "df = hvsampledata.stocks(\"pandas\", engine_kwargs={\"index_col\" : \"date\"})\n",
+    "\n",
+    "plot1 = df.hvplot(group_label=\"Company\", grid=\"x\", width=400, title=\"grid='x'\")\n",
+    "plot2 = df.hvplot(group_label=\"Company\", grid=\"y\", width=400, title=\"grid='y'\")\n",
+    "\n",
+    "plot1 + plot2"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "7c6cc816-2cc3-4af6-94a5-ed04b3bfe3ce",

hvplot/converter.py

@@ -975,7 +975,16 @@ def __init__(
             plot_opts['logy'] = logy
 
         if grid is not None:
-            plot_opts['show_grid'] = grid
+            if isinstance(grid, str):
+                gridstyle = {}
+                axis = grid[0]
+                other_axis = 'x' if axis == 'y' else 'y'
+                if len(grid) > 0:
+                    line_dash = grid[1:].lstrip('-').lstrip('.').lstrip('_')
+                    gridstyle[f'{axis}grid_line_dash'] = line_dash
+                gridstyle[f'{other_axis}grid_line_alpha'] = 0
+                plot_opts['gridstyle'] = gridstyle
+            plot_opts['show_grid'] = bool(grid)
 
         if legend is not None:
             plot_opts['show_legend'] = bool(legend)

hvplot/tests/testoptions.py

@@ -528,6 +528,31 @@ def test_bgcolor(self, df, backend):
         opts = Store.lookup_options(backend, plot, 'plot')
         assert opts.kwargs['bgcolor'] == 'black'
 
+    @pytest.mark.parametrize('grid_bool', [True, False])
+    def test_grid_boolean(self, df, backend, grid_bool):
+        plot = df.hvplot('x', 'y', grid=grid_bool)
+        opts = Store.lookup_options(backend, plot, 'plot')
+        assert opts.kwargs['grid'] is grid_bool
+
+    def test_grid_x(self, df, backend):
+        plot = df.hvplot('x', 'y', grid='x')
+        opts = Store.lookup_options(backend, plot, 'plot')
+        assert opts.kwargs['grid'] is True
+        assert opts.kwargs['gridstyle'] == {'ygrid_line_alpha': 0}
+
+    def test_grid_y(self, df, backend):
+        plot = df.hvplot('x', 'y', grid='y')
+        opts = Store.lookup_options(backend, plot, 'plot')
+        assert opts.kwargs['grid'] is True
+        assert opts.kwargs['gridstyle'] == {'xgrid_line_alpha': 0}
+
+    @pytest.mark.parameterize('grid_str', ['x-dashed', 'xdashed', 'x.dashed', 'x_dashed'])
+    def test_grid_line_dash(self, df, backend, grid_str):
+        plot = df.hvplot('x', 'y', grid=grid_str)
+        opts = Store.lookup_options(backend, plot, 'plot')
+        assert opts.kwargs['grid'] is True
+        assert opts.kwargs['gridstyle'] == {'ygrid_line_alpha': 0, 'xgrid_line_dash': 'dashed'}
+
 
 @pytest.fixture(scope='module')
 def da():