Create selections.md

Author: LiamConnors

doc/python/selections.md

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+---
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+  plotly:
+    description: How to use selections in Python. Examples of adding and styling selections.
+    display_as: file_settings
+    language: python
+    layout: base
+    name: Selections
+    order: 26
+    permalink: python/selections/
+    thumbnail: thumbnail/make_selection.png
+---
+
+## Adding Selections
+
+*New in 5.10*
+
+You can add persistent selections to a rendered figure using the **Box Select** and **Lasso Select** tools in the mode bar.
+To add multiple selections, select **Shift** when making new selections.
+To clear a selection, double-click it. You can clear all selections by double-clicking any unselected area of the figure.
+
+
+
+You can also add selections to a figure that displays when it renders using `fig.add_selection`.
+Here, we add a rectangular selection that connects the points `3.0`, `6.5`, `3.5`, and `5.5`.
+
+
+```python
+import plotly.express as px
+
+df = px.data.iris()
+
+fig = px.scatter(df, x="sepal_width", y="sepal_length")
+fig.add_selection(type="rect", x0=3.0, y0=6.5, x1=3.5, y1=5.5)
+
+fig.show()
+```
+
+## Styling Selections
+
+
+In the above example, we added a selection to the figure that is displayed when the figure renders.
+`fig.add_selection` accepts additional properties that you can use to style the selection. Here, we add a `color`, `width`, and specify the `dash` type for the selection.
+
+
+```python
+import plotly.express as px
+
+df = px.data.iris()
+
+fig = px.scatter(df, x="sepal_width", y="sepal_length")
+fig.add_selection(type="rect",
+    x0=2.5, y0=6.5, x1=3.5, y1=5.5,
+    line=dict(
+        color="Crimson",
+        width=2,
+        dash="dash",
+    ))
+
+fig.show()
+
+```
+
+## Fill Color for Active Selections
+
+You can style active selections with `activeselection`. In this example, we set active selections to appear with a `fillcolor` of `blue`.
+
+```python
+import plotly.express as px
+
+df = px.data.iris()
+
+fig = px.scatter(df, x="sepal_width", y="sepal_length")
+fig.add_selection(type="rect", x0=3.0, y0=6.5, x1=3.5, y1=5.5)
+
+fig.update_layout(dragmode='select',
+                  activeselection=dict(fillcolor='blue'))
+
+fig.show()
+```
+
+## Styling New Selections
+
+You can style new selections made on the figure by setting properties on `newselection`.
+Try making a new selection on the figure to try it out.
+
+```python
+import plotly.express as px
+
+df = px.data.iris()
+
+fig = px.scatter(df, x="sepal_width", y="sepal_length")
+
+fig.update_layout(dragmode='select',
+                  newselection=dict(line=dict(color='blue')))
+
+fig.show()
+```
+
+## More on Selections
+
+For more on selections, see the [selections section of the `dcc.Graph` page](https://dash.plotly.com/dash-core-components/graph#selections) in the Dash docs.