Plotly：着色線段

Question

如何使用 plotly 為單個線段分配顏色？

示例：繪制一條拋物線，其中線條顏色表示其斜率。

import numpy as np
from plotly import graph_objects as go

x = np.linspace(-1, 1, 101)
y = x**2
# Slope in-between of the knots
dy = (x[1:] + x[:-1])
 
fig = go.Figure()
fig.add_scatter(x=x, y=y)

Answer 1

我認為你必須分段添加它：

import numpy as np
from plotly import graph_objects as go

x = np.linspace(-1, 1, 101)
y = x**2
# Slope in-between of the knots
dy = (x[1:] + x[:-1])
line_cols = np.where(dy > 0,"#F2F013","#2F86A6")

fig = go.Figure()
for i, col in enumerate(line_cols):
    fig.add_scatter(x=x[i:(i+2)], y=y[i:(i+2)],line=dict(color=col),
                    mode='lines',showlegend=False)

fig.show()

Answer 2

• 您需要對每個顏色段進行跟蹤
• Plotly Express方法很容易用於此

import numpy as np
import plotly.express as px

x = np.linspace(-1, 1, 101)
y = x**2
# Slope in-between of the knots
dy = (x[1:] + x[:-1])

# all arrays need to be same length
fig = px.line(x=x, y=y, color=np.pad(dy, (1,0), mode="edge")>0)
fig.update_layout(showlegend=False)