在基于列的折线图中添加参考线答案

【问题标题】：adding reference line in line chart based on a column在基于列的折线图中添加参考线
【发布时间】：2021-08-07 07:57:51
【问题描述】：

我有一个这样的数据框样本

我想绘制一个折线图，x 轴为索引，y 轴为振幅，我正在使用

我有一个折线图，但如何添加参考线以显示地震发生在我期待这样或类似图表的点

【问题讨论】：

标签： python pandas matplotlib plotly

【解决方案1】：

如果您使用的是 4.12.0 的 plotly > 版本，则可以使用 plotly.express 的“add_vline”： https://plotly.com/python/horizontal-vertical-shapes/

import plotly.express as px

data={"date":["2007-10-02 00:00:00","2007-10-02 00:00:20","2007-10-02 00:00:40","2007-10-02 00:01:00"],
    "ampli":[35,39.37,39.48,36],"quake":[np.nan,np.nan,4.3,np.nan]}



df=pd.DataFrame(data)
df['date']=pd.to_datetime(df['date'],format="%Y/%m/%d %H:%M:%S")

df.set_index("date",inplace=True)
df_quake = df[df['quake'].notna()]

fig2=px.line(df,x=df.index, y="ampli",title="ampli")
fig2.add_vline(x=df_quake.index, line_width=3, line_dash="dash", line_color="green")
plotly.offline.plot(fig2, filename='test2.html')

否则，你可以尝试用 graph_object 做一些事情：

import pandas as pd
import plotly.graph_objects as go
import plotly

import numpy as np


data={"date":["2007-10-02 00:00:00","2007-10-02 00:00:20","2007-10-02 00:00:40","2007-10-02 00:01:00"],
    "ampli":[35,39.37,39.48,36],"quake":[np.nan,np.nan,4.3,np.nan]}



df=pd.DataFrame(data)
df['date']=pd.to_datetime(df['date'],format="%Y/%m/%d %H:%M:%S")

df.set_index("date",inplace=True)
df_quake = df[df['quake'].notna()]


fig = go.Figure()
fig.add_trace(go.Scatter(x=df.index, y=df["ampli"],
                    mode='lines',
                    name='lines'))
fig.add_trace(go.Scatter(x=df_quake.index, y=df_quake["ampli"],
                    mode='markers',
                    name='quake',
                    marker={'size':10}))
plotly.offline.plot(fig, filename='test.html')

结果：

【讨论】：