Plotly极坐标图：坐标轴与背景颜色设置问题

你遇到的0度方向线条过粗问题，本质是径向轴（radialaxis）的轴线和角轴（angularaxis）的0度网格线叠加导致的——两者在0度位置重合，线条宽度相加，视觉上就比其他线条更粗。

两种解决方法： #

方法1：关闭径向轴的轴线显示

径向轴的轴线和角轴0度网格线功能重复，直接关闭径向轴的轴线即可避免叠加：
修改radialaxis配置中的showline为False：

radialaxis = dict(
    side = "counterclockwise",
    showline = False,  # 关闭径向轴轴线
    linewidth = 2,
    gridcolor = "black",
    gridwidth = 2,
)

方法2：统一径向轴与角轴的线条宽度

如果需要保留径向轴的轴线，将两者的linewidth设为相同值，叠加后粗细会保持一致：
比如都设为3：

angularaxis = dict(
    linewidth = 3,
    showline=True,
    linecolor='black',
    gridcolor = "black"
),
radialaxis = dict(
    side = "counterclockwise",
    showline = True,
    linewidth = 3,  # 和角轴linewidth保持一致
    gridcolor = "black",
    gridwidth = 2,
)

修改后的完整代码（以方法1为例）： #

import plotly.graph_objects as go
import pandas as pd

df = pd.read_csv("https://raw.githubusercontent.com/plotly/datasets/master/hobbs-pearson-trials.csv")

fig = go.Figure()

fig.add_trace(go.Scatterpolargl(
      r = df.trial_1_r,
      theta = df.trial_1_theta,
      name = "Trial 1",
      marker=dict(size=10, color="mediumseagreen")
    ))

# Common parameters for all traces
fig.update_traces(mode="markers", marker=dict(line_color='black', opacity=0.7))

fig.update_layout(
    title = "",
    font_size = 15,
    showlegend = False,
    polar = dict(
      bgcolor = "rgb(223, 223, 223)",
      angularaxis = dict(
        linewidth = 3,
        showline=True,
        linecolor='black',
        gridcolor = "black"
      ),
      radialaxis = dict(
        side = "counterclockwise",
        showline = False,  # 关闭径向轴轴线
        linewidth = 2,
        gridcolor = "black",
        gridwidth = 2,
      )
    ),
    paper_bgcolor = "white"
)

fig.show()

fig.write_image("plotlyPolar.svg", scale=2)
fig.write_image("plotlyPolar.jpg", scale=3)

内容的提问来源于stack exchange，提问作者Pugl