Create Subplots in For Loop Matplotlib

Question

i'm trying to make a 3,2 subplot using matplotlib and I'm not understanding how to do this after reading the documentation as it applies to my code as follows:

import pandas as pd
from sys import exit
import numpy as np
import matplotlib.pyplot as plt
import datetime
import xarray as xr
import cartopy.crs as ccrs
import calendar

list = [0,1,2,3,4,5]
now = datetime.datetime.now()
currm = now.month
import calendar
fig, axes = plt.subplots(nrows=3,ncols=2)
fig.subplots_adjust(hspace=0.5)
fig.suptitle('Teleconnection Pos+ Phases {} 2020'.format(calendar.month_name[currm-1]))
#for x in list: 
#for ax, x in zip(axs.ravel(), list):
for x, ax in enumerate(axes.flatten()):
        dam = DS.where(DS['time.year']==rmax.iloc[x,1]).groupby('time.month').mean()#iterate by index 
of column "1" or the years
        dam = dam.sel(month=3)#current month mean 500
        dam = dam.sel(level=500)
        damc = dam.to_array()
        lats = damc['lat'].data
        lons = damc['lon'].data
#plot data
        ax = plt.axes(projection=ccrs.PlateCarree())
        ax.coastlines(lw=1)
        damc = damc.squeeze()
        ax.contour(lons,lats,damc,cmap='jet')
        ax.set_title(tindices[x])
        plt.show()
#plt.clf()

I've tried multiple options some of which are above in the comments and I cannot get the subplots to show in the 3,2 subplot i'm expecting. I only get single plots. I've included the first plot in the for loop below as you can see it's not plotted inside the 3,2 subplot region:

[![enter image description here][1]][1]

The row with "ax.contour" may be the problem but i'm not sure. Thank you very much and here below is my target subplot region:

[![enter image description here][1]][1]

Please include all import lines at top of code and ideally sample data for reproducible example. Also, your description of issue is not quite clear. If six plots render on one column, what is the issue? — Parfait
– Parfait, Commented Apr 10, 2020 at 20:24
Sorry, my code is quite long so my focus is on the for loop and i've added a few lines at the top now. I've edited the question to drive home the point that I'm not getting subplots at all - i just get 6 plots total, generated one at a time in the loop. Hope this is more clear. Thank you — user2100039
– user2100039, Commented Apr 10, 2020 at 20:39

Parfait · Accepted Answer · 2020-04-10 22:25:01Z

2

Without a reproducible sample data, below cannot be tested. However, your loop assigns a new ax and does not use the ax being iterating on. Additionally, plt.show() is placed within the loop. Consider below adjustment

for x, ax in enumerate(axes.flatten()):
    ...
    ax = plt.axes(projection=ccrs.PlateCarree())
    ...
    plt.show()

Consider placing projection in the plt.subplots and then index axes within loop:

fig, axes = plt.subplots(nrows=3, ncols=2, subplot_kw={'projection': ccrs.PlateCarree()})
fig.subplots_adjust(hspace=0.5)
fig.suptitle('Teleconnection Pos+ Phases {} 2020'.format(calendar.month_name[currm-1]))

axes = axes.flatten()

for x, ax in enumerate(axes):
        dam = DS.where(DS['time.year']==rmax.iloc[x,1]).groupby('time.month').mean()

        dam = dam.sel(month=3)#current month mean 500
        dam = dam.sel(level=500)
        damc = dam.to_array()
        lats = damc['lat'].data
        lons = damc['lon'].data

        axes[x].coastlines(lw=1)
        damc = damc.squeeze()
        axes[x].contour(lons, lats, damc, cmap='jet')
        axes[x].set_title(tindices[x])

plt.show() 
plt.clf()

edited Apr 10, 2020 at 22:25

answered Apr 10, 2020 at 21:01

Parfait

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5 Comments

user2100039 Over a year ago

Thanks for this - i get the 3,2 subplot grid in blank rectangles right away but this error immediately in the first loop iteration: AttributeError: 'numpy.ndarray' object has no attribute 'coastlines'

Parfait Over a year ago

Try replacing all axes[x] with ax in loop.

user2100039 Over a year ago

i had to change this first line to this for the projection--> fig, axes = plt.subplots(nrows=3,ncols=2,subplot_kw={'projection': ccrs.PlateCarree()})....it's working or attempting but i just have the 1st plot in the upper left or position 1,1 and all the other spaces are completely empty/white. There are no errors as it completes. i replaced the axes[x] as you suggstd in the loop.

Parfait Over a year ago

See update. We need to flatten axes before not during loop.

user2100039 Over a year ago

it works! moving the plt.show() and plt.clf() outside the loop did the trick- thank you!!

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