python - 用 fig.update_traces 用虚线和标记突出显示线

Question

我正在尝试在 Plotly 中制作一个折线图，带有虚线和标记线。在这种情况下，我希望代表“加拿大”的线被点缀。我已经想出如何更改宽度和颜色，但无法弄清楚如何使线条变成虚线。我原来的 DF 大得多，所以 go.scatter 对我来说不是一个解决方案。感谢您的帮助!

import plotly.express as px

# data
df = px.data.gapminder()
df = df[df['country'].isin(['Canada', 'USA', 'Norway', 'Sweden', 'Germany'])]

# plotly
fig = px.line(df, x='year', y='lifeExp',
              color='country')

# color "Canada" black and change the width of the line
fig.update_traces(patch={"line": {"color": "black", "width": 4}},#
                  selector={"legendgroup": "Canada"})

#i tried to extend the code with dash and mode, but do not work:
#fig.update_traces(patch={"line": {"color": "black", "width": 4, "dash": 'dot', "mode": 'lines+markers'}}, 

plotly.io.write_image(fig, file='testline.png', format='png')

我希望一条黑色虚线最终看起来像这样。

Answer 1

您的代码中的错误是您将 mode 设置为 lines+markers，这是折线图中的无效属性。有效的代码如下所示:

import plotly.express as px

# data
df = px.data.gapminder()
df = df[df['country'].isin(['Canada', 'USA', 'Norway', 'Sweden', 'Germany'])]

# plotly
fig = px.line(df, x='year', y='lifeExp',
              color='country')

fig.update_traces(patch={"line": {"color": "black", "width": 4}})
fig.update_traces(patch={"line": {"color": "black", "width": 4, "dash": 'dot'}}, selector={"legendgroup": "Canada"}) 

fig.show()

并返回了这样的图表: