Update selections.md

Author: LiamConnors

doc/python/selections.md

@@ -138,15 +138,123 @@ fig.show()
 
 ## Selections with Time Series
 
-Selections are also supported on time series figures. Here, we add a rectangular selection with a region between the dates `2019-01-01"` and `"2019-10-01"` on the x axis and between `1` and `1.15` on the y axis.
+Selections are also supported on time series figures. Here, we add a rectangular selection with a region between the dates `2019-01-01"` and `"2019-10-01"` on the x axis and between `0.95` and `1.17` on the y axis.
 
 
 ```python
 import plotly.express as px
 
 df = px.data.stocks()
 fig = px.line(df, x='date', y="GOOG")
-fig.add_selection(x0="2019-01-01", y0=1, x1="2019-10-01", y1=1.17)
+fig.add_selection(x0="2019-01-01", y0=0.95, x1="2019-10-01", y1=1.17)
+fig.show()
+```
+
+## Selections on Subplots
+
+
+You can add selections to subplots by specifying axis ids using `xaxis` and `yaxis`. Here, we add one selection on the plot with axis ids `x` and `y2` and two selections to the the plot with axis ids `x` and `y`.
+
+```python
+import plotly.graph_objects as go
+
+import numpy as np
+
+t = np.linspace(-1, 1.2, 2000)
+x = (t**3) + (0.3 * np.random.randn(2000))
+y = (t**6) + (0.3 * np.random.randn(2000))
+
+fig = go.Figure()
+fig.add_trace(go.Histogram2dContour(
+        x = x,
+        y = y,
+        colorscale = 'Blues',
+        reversescale = True,
+        xaxis = 'x',
+        yaxis = 'y'
+    ))
+fig.add_trace(go.Scatter(
+        x = x,
+        y = y,
+        xaxis = 'x',
+        yaxis = 'y',
+        mode = 'markers',
+        marker = dict(
+            color = 'rgba(0,0,0,0.3)',
+            size = 3
+        )
+    ))
+fig.add_trace(go.Histogram(
+        y = y,
+        xaxis = 'x2',
+        marker = dict(
+            color = 'rgba(0,0,0,1)'
+        )
+    ))
+fig.add_trace(go.Histogram(
+        x = x,
+        yaxis = 'y2',
+        marker = dict(
+            color = 'rgba(0,0,0,1)'
+        )
+    ))
+
+fig.update_layout(
+    autosize = False,
+    xaxis = dict(
+        zeroline = False,
+        ___domain = [0,0.85],
+        showgrid = False
+    ),
+    yaxis = dict(
+        zeroline = False,
+        ___domain = [0,0.85],
+        showgrid = False
+    ),
+    xaxis2 = dict(
+        zeroline = False,
+        ___domain = [0.85,1],
+        showgrid = False
+    ),
+    yaxis2 = dict(
+        zeroline = False,
+        ___domain = [0.85,1],
+        showgrid = False
+    ),
+    height = 600,
+    width = 600,
+    bargap = 0,
+    hovermode = 'closest',
+    showlegend = False,
+    selections = [{
+      "x0": 0.5,
+      "x1": -0.5,
+      "xref": "x",
+      "y0": 190,
+      "y1": 0,
+      "yref": "y2",
+        "line":dict(color="yellow")
+    }, {
+      "x0": -0.2,
+      "x1": -1.5,
+      "xref": "x",
+      "y0": 2,
+      "y1": -1,
+      "yref": "y",
+        "line":dict(
+        color="yellow"
+    )
+    }, {
+      "path": "M0.75,2.39L0.98,3.38L1.46,3.68L1.80,3.35L2.01,2.51L1.67,1.15L1.18,0.50L0.65,0.66L0.54,0.83L0.49,1.56Z",
+      "xref": "x",
+      "yref": "y",
+            "line":dict(
+        color="yellow"
+    )
+    }]
+)
+
+
 fig.show()
 ```