Add vertical line across subplots that have the same datetime axis

Question

I have been trying to add a vertical line across subplots that have the same DateTime x axis. The code i am using is:

import datetime as dt
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import pickle

# Import data for minimum reproducible example #
file_to_read = open("example.dat", "rb")

B = pickle.load(file_to_read)

file_to_read.close()

## I would like to use something like this to locate the 
## point that correspond to that datetime and plot the vertical line
dt2 = pd.to_datetime("2018-10-31 06:43:10.000000")
dt3  = pd.to_datetime("2018-10-31 06:43:35.600000")

s2  = B.index.unique().get_loc(dt2, method='nearest')
s2a  = B.index.unique().get_loc(dt3, method='nearest')


size=21
int1=1
fig, axs = plt.subplots(2, sharex=True)

axs[1].plot(B.L,linewidth=3,label='$B_{z}$')
axs[1].plot(B.M,linewidth=3,label='$B_{y}$')
axs[1].plot(B.N,linewidth=3,label='$B_{x}$')
axs[1].tick_params(axis='both',labelsize=size-3)
axs[1].legend( fontsize=size)
axs[1].legend(frameon=False, loc='upper left', ncol=3, fontsize=size)
axs[1].set_ylim([-80,50])
axs[1].set_ylabel(r'$B_{NML} \ (nT)$', fontsize=size)


axs[0].plot(B.Total,linewidth=3,color='black',label='$|B|$')
axs[0].legend(loc=4, fontsize=size)
axs[0].legend(frameon=False, loc='lower left', ncol=1, fontsize=size)
axs[0].tick_params(axis='both',labelsize=size-3)
axs[0].set_ylim([0,90])
axs[0].set_ylabel(r'$B_{tot} \ (nT)$', fontsize=size)

## axis limits ##
axs[0].set_xlim([dt2, dt3])

## Add title ##
fig.text(0.5, 0.9, '2018 Oct 31', ha='center', va='center',fontsize=size)

## Gap between subplots
plt.subplots_adjust(wspace=0.01, hspace=0.12)

## add vertical line ##
line = plt.Line2D((.42,.42),(.125,.88),color='b',linewidth=1)
line2 = plt.Line2D((.55,.55),(.125,.88),color='b',linewidth=1)
fig.add_artist(line)
fig.add_artist(line2)


plt.plot()

I was able to add a vertical line but I would like to automate the process. Inserting for example the DateTime and plot this instead of guessing the point in the graph that corresponds to this datetime. For example using something like this:

dt2 = pd.to_datetime("2018-10-31 06:43:10.000000")
dt3  = pd.to_datetime("2018-10-31 06:43:35.600000")

s2  = B.index.unique().get_loc(dt2, method='nearest')
s2a  = B.index.unique().get_loc(dt3, method='nearest')

The data required for minimum reproducible example can be found here: https://www.dropbox.com/s/w9gblp3dc361nw6/example.dat?dl=0

does [this](https://stackoverflow.com/q/6146290/10197418) provide a way to achieve this? — FObersteiner, Feb 13 '21 at 12:48
@MrFuppes No I am sorry I have already trid this! The difference is that here the x axis is datetime! — , Feb 13 '21 at 12:49
Hm axvline should work nevertheless, see e.g. [here](https://stackoverflow.com/a/66132942/10197418) — FObersteiner, Feb 13 '21 at 13:11

score 1 · Accepted Answer · edited Feb 13 '21 at 15:18

1

Like @MrFuppes said, if you don't care about don't having a line between the both subfigures, axvline should be enough:

dt5 = B.index[5]
dt10 = B.index[10]
    
axs[0].axvline(dt5, color='r', ls='dashed')
axs[1].axvline(dt5, color='r', ls='dashed')
    
axs[0].axvline(dt10, color='k', ls='dashed')
axs[1].axvline(dt10, color='k', ls='dashed')

Example

edited Feb 13 '21 at 15:18

FObersteiner

22,500
8
42
72

answered Feb 13 '21 at 15:09

viniciusrf1992

313
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did you try the `clip_on=False` keyword as shown in the other question I linked? this should make the line visible between the subplots (didn't test this though...) [*docs*](https://matplotlib.org/stable/api/_as_gen/matplotlib.artist.Artist.set_clip_on.html) – FObersteiner Feb 13 '21 at 15:22
1

@MrFuppes Yes `clip_on=False` works when the y-coordinates are adjusted to extend the lines from the top ax or from the bottom ax over the gap. – Patrick FitzGerald Feb 13 '21 at 19:48

Add vertical line across subplots that have the same datetime axis

1 Answers1