Python - plotly assigning scatterplot colors by label

问题

I'm trying to replicate one of the basic examples in Plotly R https://plot.ly/r/line-and-scatter/#qualitative-colorscales into Plotly Python. But finding it impossible.

The same problem is also solved in R here: Plotly assigning colors based on label

```

trace0 = go.Scatter( x = x1, y = y1, mode = 'markers',
                    name = ytitle +  ' X vs ' + Atitle, 
                    marker=dict(size=4, symbol='circle', 
                                color=colorsIdx, colorbar= go.ColorBar(title= 'colorbar'),
                            colorscale='Viridis')
                    )

```

The closest I've gotten is using a colorbar, but that is suboptimal since I can't figure out how to pick colors so that they don't blend together, and then the color legend makes the graph look like there's some continuous data going on which is not the case.

回答1:

Use a dictionary and map the colors accordingly:

import pandas as pd 
import plotly.plotly as py
import plotly.graph_objs as go

d  = {'x': [1, 2, 3], 'y': [3, 4, 5], 'z': ['A', 'B', 'A']}
df = pd.DataFrame(data=d)

colorsIdx = {'A': 'rgb(215,48,39)', 'B': 'rgb(215,148,39)'}
cols      = df['z'].map(colorsIdx)

# Create a trace
trace = go.Scatter(
    x = df.x,
    y = df.y,
    mode = 'markers',
    marker=dict(size=15, color=cols)
)

data = [trace]
py.iplot(data)

来源：https://stackoverflow.com/questions/49885837/python-plotly-assigning-scatterplot-colors-by-label