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

Answer 1

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.

Answer 2

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:

Answer 3

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!