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Merged
merged 6 commits into from
Nov 14, 2019
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cmid&zmid #179

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cmid&zmid
Nov 7, 2019
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Merge branch 'master' into cmid_zmid_py_
emmanuelle Nov 12, 2019
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seperated examples for cmid-zmid
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Merge branch 'cmid_zmid_py_' of https://github.com/plotly/plotly.py-d…
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43 changes: 39 additions & 4 deletions python/colorscales.md
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ jupyter:
extension: .md
format_name: markdown
format_version: '1.1'
jupytext_version: 1.1.1
jupytext_version: 1.2.1
kernelspec:
display_name: Python 3
language: python
Expand All @@ -20,7 +20,7 @@ jupyter:
name: python
nbconvert_exporter: python
pygments_lexer: ipython3
version: 3.6.8
version: 3.7.3
plotly:
description: How to set colorscales and heatmap colorscales in Python and Plotly.
Divergent, sequential, and qualitative colorscales.
Expand All @@ -32,8 +32,8 @@ jupyter:
name: Colorscales
order: 22
permalink: python/colorscales/
thumbnail: thumbnail/heatmap_colorscale.jpg
redirect_from: python/logarithmic-color-scale/
thumbnail: thumbnail/heatmap_colorscale.jpg
v4upgrade: true
---

Expand Down Expand Up @@ -196,6 +196,41 @@ fig.add_trace(go.Heatmap(
fig.show()
```

### Colorscale Midpoint
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Setting the midpoint of a diverging colorscale

The following example uses [cmid](https://plot.ly/python/reference/#scatter-marker-cmid) attribute to set the mid-point of the color domain by scaling [cmin](https://plot.ly/python/reference/#scatter-marker-cmin) and/or [cmax](https://plot.ly/python/reference/#scatter-marker-cmax) to be equidistant to this point. It only has impact when [marker.line.color](https://plot.ly/python/reference/#scattercarpet-marker-line-color) sets to a numerical array, and [marker.line.cauto](https://plot.ly/python/reference/#scattercarpet-marker-line-cauto) is `True`. The heatmap chart uses [zmid](https://plot.ly/python/reference/#heatmap-zmid) attribute to set the mid-point of the color domain by scaling [zmin](https://plot.ly/python/reference/#heatmap-zmin) and/or [zmax](https://plot.ly/python/reference/#heatmap-zmax) to be equidistant to this point.
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I think it's marker.color and not marker.line.color?


```python
import plotly.graph_objects as go

fig = go.Figure()

fig.add_trace(go.Scatter(
y=[1, 2, 0, 1],
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the data should range from, say -5 to +15

mode="markers",
marker={
"size": 25,
"color": [1,4,8],
"cmid": 0,
"colorbar": {
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let's remove the colorbar settings

"len": 0.5,
"y": 1,
"yanchor": "top",
"title": {"text": "cmid=0", "side": "right"}
}}))

fig.add_trace(go.Heatmap(
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let's just use 1 trace here.

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maybe make a separate plot for the heatmap and say "heatmap uses zmid to do the same thing"

z=[[1, 5, 3, 2], [5, 3, 7, 9], [3, 2, 6, 4]],
zmid=10,
colorbar={
"len": 0.5,
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maybe you could use here a colormap for which the midpoint is white, like 'RdBu', so that the midpoint is more visible.

"y": 0.5,
"yanchor": "top",
"title": {"text": "zmid=10", "side": "right"}
}))

fig.show()
```

### Custom Contour Plot Colorscale

```python
Expand Down Expand Up @@ -271,7 +306,7 @@ fig = go.Figure(go.Heatmap(
[1., 'rgb(0, 0, 0)'], #100000

],
colorbar = dict(
colorbar= dict(
tick0= 0,
tickmode= 'array',
tickvals= [0, 1000, 10000, 100000]
Expand Down