how to add horizontal line in all subplots in plotly python

Question

I want to add horizontal line at 0.09 and -0.09 in every subplot I am generating in plotly. Following is my code to do that.

  trace1 = go.Scatter(
    x=df1['transaction_date'],
    y=df1['difference'],
    )
  trace2 = go.Scatter(
    x=df2['transaction_date'],
    y=df2['difference'],
)

 trace3 = go.Scatter(
   x=df3['transaction_date'],
   y=df3['difference'],

 )
 trace4 = go.Scatter(
   x=df4['transaction_date'],
   y=df4['difference'],

 )

 fig = tools.make_subplots(rows=2, cols=2,subplot_titles=('DF1 HS', DF2 HSD',
                                                     'DF3 HD', 'DF4 SD',
                                                     ))

 fig.append_trace(trace1, 1, 1)
 fig.append_trace(trace2, 1, 2)
 fig.append_trace(trace3, 2, 1) 
 fig.append_trace(trace4, 2, 2)

Then I want to save this 4 subplots as jpeg on disk. How can I do that in python

I am open to `matplotlib` as well. Can we do the same thing there? — Neil, Aug 21 '18 at 12:53

score 5 · Answer 1 · answered Jul 28 '21 at 18:54

I'm pretty new to Plotly so maybe the API has just been updated, but it seems there is a much simpler solution, per the documentation here. One need only use the fig.add_hline() syntax while specifying which subplot (col and row) it should be drawn on, as such:

fig.add_hline(y=1, line_dash="dot", row=1, col=1, line_color="#000000", line_width=2)

This line will instruct Plotly to draw a horizontal line y = 1 on the subplot located at row = 1; col = 1.

Alternatively, as noted in the dox, the "all" keyword can be passed as a value for either the row or col argument to instruct plotly to draw the line on (wait for it...) all the subplots!

score 3 · Accepted Answer · answered Aug 21 '18 at 14:09

Try updating layout of fig object with shapes as below:

import plotly.graph_objs as go
from plotly import tools
from plotly.offline import init_notebook_mode, plot

df = pd.DataFrame(np.random.randint(0,100,size=(20,2)),
                  index=pd.date_range(start='2018-08-21',end='2018-09-09'),
                  columns=['A','B'])

trace1 = go.Scatter(x=df.index,y=df['A'],)
trace2 = go.Scatter(x=df.index,y=df['B'],)

fig = tools.make_subplots(rows=2, cols=1,subplot_titles=(['A','B']))

fig.append_trace(trace1, 1, 1)
fig.append_trace(trace2, 2, 1)

fig['layout'].update(shapes=[{'type': 'line','y0':50,'y1': 50,'x0':str(df.index[0]), 
                              'x1':str(df.index[-1]),'xref':'x1','yref':'y1',
                              'line': {'color': 'red','width': 2.5}},
                             {'type': 'line','y0':50,'y1': 50,'x0':str(df.index[0]), 
                              'x1':str(df.index[-1]),'xref':'x2','yref':'y2',
                              'line': {'color': 'red','width': 2.5}}])

plot(fig,show_link=False,image='jpeg',image_filename='Temp_plot')

The plot will be saved as Temp_plot.jpeg. Check the image below.

The downside of this method is we need to carefully give axes values to xref and yref with respect to subplots.

These days we can also just use vline or hline e.g. like here https://stackoverflow.com/a/65218725/5765802 — Joey, Dec 09 '20 at 14:30

Dodge · Answer 3 · 2018-08-21T15:05:17.393

You mentioned that you were ok with a `matplotlib` solution:

Data:

dict = {
    "a":np.random.randint(low=-10,high=10,size=20),
    "b":np.random.randint(low=-10,high=10,size=20),
    "c":np.random.randint(low=-10,high=10,size=20),
    "d":np.random.randint(low=-10,high=10,size=20),
}

df = pd.DataFrame(dict)

Plot:

fig, axes = plt.subplots(2,2, figsize=(20,10), sharex=True, sharey=True)
for i,j in zip(axes.ravel(), list(df)):
    i.plot(df.index, df[j], 'ro')
    i.hlines(y=-3, xmin=0, xmax=22)
    i.hlines(y=3, xmin=0, xmax=22)

fig.savefig("testplot.png")

Result:

how to add horizontal line in all subplots in plotly python

3 Answers3

You mentioned that you were ok with a matplotlib solution:

You mentioned that you were ok with a `matplotlib` solution: