如何在图形甘纳特图表中为元素指定颜色？

Question

我在这里学习python教程：https://plotly.com/python/gantt/

import pandas as pd
import plotly.express as px
df = pd.DataFrame([
    dict(Task="Job A", Start='2009-01-01', Finish='2009-02-25'),
    dict(Task="Job A", Start='2009-02-26', Finish='2009-03-28'),
    dict(Task="Job B", Start='2009-03-05', Finish='2009-04-15'),
    dict(Task="Job C", Start='2009-02-20', Finish='2009-05-30')
])

print(df)

    Task       Start      Finish
0  Job A  2009-01-01  2009-02-25
1  Job A  2009-02-26  2009-03-28
2  Job B  2009-03-05  2009-04-15
3  Job C  2009-02-20  2009-05-30

上面教程中的代码给了我图表：

fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task")
fig.update_yaxes(autorange="reversed") # otherwise tasks are listed from the bottom up
fig.show()

请注意，作业A有两个事件。

我想为每个开始和结束交替颜色。例如第一事件红色、第二事件蓝色、第三事件红色、第四事件蓝色等。

我已经尝试了color_discrete_sequence和color_discrete_map参数，但是颜色不交替。

我所尝试的：

fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task",color_discrete_sequence=["red", "blue"])
fig.update_yaxes(autorange="reversed") 
fig.show()

和

fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task",color_discrete_map={"Start": "red","Finish":'blue'})
fig.update_yaxes(autorange="reversed") 
fig.show()

有什么关于如何交替颜色的想法吗？

我希望A工作看起来像什么的一个例子：

Answer 1

只需添加一个描述所需颜色的列。

import pandas as pd
import plotly.express as px
df = pd.DataFrame([
    dict(Task="Job A", Start='2009-01-01', Finish='2009-02-25', Color='blue'),
    dict(Task="Job A", Start='2009-02-26', Finish='2009-03-28', Color='red'),
    dict(Task="Job B", Start='2009-03-05', Finish='2009-04-15', Color='blue'),
    dict(Task="Job C", Start='2009-02-20', Finish='2009-05-30', Color='blue')
])

fig = px.timeline(df, x_start="Start", x_end="Finish", y="Task", color="Color")
fig.update_yaxes(autorange="reversed") # otherwise tasks are listed from the bottom up
fig.show()