Single Colorbar for multiple subplots

Hi,

I am trying to plot 4 subplots in a 2 by 2 grid for mean sea level pressure
data over the four seasons.

I have managed to plot all four in the same figure with their own individual
colorbars, however, I would ideally like the figure to display one colorbar
at the bottom to represent all four figures and I have been unsuccessful in
doing this so far. There have been a few posts on this but as this is my
first assignment (i'm a student at university) with python, I'm struggling
to understand the answers!

The section of my code which involves the plotting of data is as follows:

...
#Select Projection
lon_0= 0
lat_0=lats.mean()

m = Basemap(projection = 'cyl', lat_0=lat_0, lon_0=lon_0, resolution = 'l')
#Convert Lons and Lats
x,y = np.meshgrid (lons_shifted,lats)
xx,yy= m(x,y)

v = np.linspace(980, 1030, 11, endpoint=True)

fig = plt.figure()

plt.subplot(2, 2, 1)
set1 = m.contourf(xx,yy,MSLP_WINTER, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Winter')
bar = plt.colorbar(orientation = 'horizontal', ticks = v, format = '%.0f')
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 2)
set2 = m.contourf(xx,yy,MSLP_SPRING, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Spring')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 3)
set3 = m.contourf(xx,yy,MSLP_SUMMER, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Summer')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 4)
set4 = m.contourf(xx,yy,MSLP_AUTUMN, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Autumn')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.suptitle("Seasonally Averaged Mean Sea Level Pressure between 2006 to
2016")

plt.show()

This creates the following image:
<http://matplotlib.1069221.n5.nabble.com/file/n48091/MSLP_Seasonal_Averages.png>

Any help would be very much appreciated.
Also, if there any obvious bad habits within this code, please feel free to
point them out!

Thanks,
Dan

···

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I modified matplotlib to let you do this by passing an array of axes to the ax argument of colorbar. It's in the git master branch but that has other bugs so you may not want to use it yet.

But the way to do this with older releases is to make the axis you want to put the colorbar in manually (cbax=fig.add_axes) with the correct position and then pass cbax to colorbar as the argument to the parameter cax. Of course you may need to make the other subplots smaller prob using the subplots_adjust method if the figure.

Cheers. Jody

···

Sent from my iPhone

On Jul 19, 2017, at 07:31, danjames95 <danjames95 at live.co.uk> wrote:

Hi,

I am trying to plot 4 subplots in a 2 by 2 grid for mean sea level pressure
data over the four seasons.

I have managed to plot all four in the same figure with their own individual
colorbars, however, I would ideally like the figure to display one colorbar
at the bottom to represent all four figures and I have been unsuccessful in
doing this so far. There have been a few posts on this but as this is my
first assignment (i'm a student at university) with python, I'm struggling
to understand the answers!

The section of my code which involves the plotting of data is as follows:

...
#Select Projection
lon_0= 0
lat_0=lats.mean()

m = Basemap(projection = 'cyl', lat_0=lat_0, lon_0=lon_0, resolution = 'l')
#Convert Lons and Lats
x,y = np.meshgrid (lons_shifted,lats)
xx,yy= m(x,y)

v = np.linspace(980, 1030, 11, endpoint=True)

fig = plt.figure()

plt.subplot(2, 2, 1)
set1 = m.contourf(xx,yy,MSLP_WINTER, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Winter')
bar = plt.colorbar(orientation = 'horizontal', ticks = v, format = '%.0f')
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 2)
set2 = m.contourf(xx,yy,MSLP_SPRING, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Spring')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 3)
set3 = m.contourf(xx,yy,MSLP_SUMMER, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Summer')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.subplot(2, 2, 4)
set4 = m.contourf(xx,yy,MSLP_AUTUMN, v)
m.drawmapboundary()
m.drawcoastlines()
plt.title('Autumn')
bar = plt.colorbar(orientation = 'horizontal', ticks = v)
plt.xlim(-80,20)
plt.ylim (20,70)

plt.suptitle("Seasonally Averaged Mean Sea Level Pressure between 2006 to
2016")

plt.show()

This creates the following image:
<http://matplotlib.1069221.n5.nabble.com/file/n48091/MSLP_Seasonal_Averages.png>

Any help would be very much appreciated.
Also, if there any obvious bad habits within this code, please feel free to
point them out!

Thanks,
Dan

--
View this message in context: http://matplotlib.1069221.n5.nabble.com/Single-Colorbar-for-multiple-subplots-tp48091.html
Sent from the matplotlib - users mailing list archive at Nabble.com.
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users at python.org
https://mail.python.org/mailman/listinfo/matplotlib-users

Another approach that I like is to use:
https://matplotlib.org/examples/axes_grid/demo_axes_grid.html

···

On Sat, Aug 5, 2017 at 1:05 PM, Klymak Jody <jklymak at uvic.ca> wrote:

I modified matplotlib to let you do this by passing an array of axes to
the ax argument of colorbar. It's in the git master branch but that has
other bugs so you may not want to use it yet.

But the way to do this with older releases is to make the axis you want to
put the colorbar in manually (cbax=fig.add_axes) with the correct position
and then pass cbax to colorbar as the argument to the parameter cax. Of
course you may need to make the other subplots smaller prob using the
subplots_adjust method if the figure.

Cheers. Jody

Sent from my iPhone

> On Jul 19, 2017, at 07:31, danjames95 <danjames95 at live.co.uk> wrote:
>
> Hi,
>
> I am trying to plot 4 subplots in a 2 by 2 grid for mean sea level
pressure
> data over the four seasons.
>
> I have managed to plot all four in the same figure with their own
individual
> colorbars, however, I would ideally like the figure to display one
colorbar
> at the bottom to represent all four figures and I have been unsuccessful
in
> doing this so far. There have been a few posts on this but as this is my
> first assignment (i'm a student at university) with python, I'm
struggling
> to understand the answers!
>
> The section of my code which involves the plotting of data is as follows:
>
> ...
> #Select Projection
> lon_0= 0
> lat_0=lats.mean()
>
> m = Basemap(projection = 'cyl', lat_0=lat_0, lon_0=lon_0, resolution =
'l')
> #Convert Lons and Lats
> x,y = np.meshgrid (lons_shifted,lats)
> xx,yy= m(x,y)
>
> v = np.linspace(980, 1030, 11, endpoint=True)
>
> fig = plt.figure()
>
> plt.subplot(2, 2, 1)
> set1 = m.contourf(xx,yy,MSLP_WINTER, v)
> m.drawmapboundary()
> m.drawcoastlines()
> plt.title('Winter')
> bar = plt.colorbar(orientation = 'horizontal', ticks = v, format =
'%.0f')
> plt.xlim(-80,20)
> plt.ylim (20,70)
>
> plt.subplot(2, 2, 2)
> set2 = m.contourf(xx,yy,MSLP_SPRING, v)
> m.drawmapboundary()
> m.drawcoastlines()
> plt.title('Spring')
> bar = plt.colorbar(orientation = 'horizontal', ticks = v)
> plt.xlim(-80,20)
> plt.ylim (20,70)
>
> plt.subplot(2, 2, 3)
> set3 = m.contourf(xx,yy,MSLP_SUMMER, v)
> m.drawmapboundary()
> m.drawcoastlines()
> plt.title('Summer')
> bar = plt.colorbar(orientation = 'horizontal', ticks = v)
> plt.xlim(-80,20)
> plt.ylim (20,70)
>
> plt.subplot(2, 2, 4)
> set4 = m.contourf(xx,yy,MSLP_AUTUMN, v)
> m.drawmapboundary()
> m.drawcoastlines()
> plt.title('Autumn')
> bar = plt.colorbar(orientation = 'horizontal', ticks = v)
> plt.xlim(-80,20)
> plt.ylim (20,70)
>
> plt.suptitle("Seasonally Averaged Mean Sea Level Pressure between 2006 to
> 2016")
>
> plt.show()
>
> This creates the following image:
> <http://matplotlib.1069221.n5.nabble.com/file/n48091/MSLP_
Seasonal_Averages.png>
>
> Any help would be very much appreciated.
> Also, if there any obvious bad habits within this code, please feel free
to
> point them out!
>
> Thanks,
> Dan
>
>
>
> --
> View this message in context: http://matplotlib.1069221.n5.
nabble.com/Single-Colorbar-for-multiple-subplots-tp48091.html
> Sent from the matplotlib - users mailing list archive at Nabble.com.
> _______________________________________________
> Matplotlib-users mailing list
> Matplotlib-users at python.org
> https://mail.python.org/mailman/listinfo/matplotlib-users

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I have managed to sort this using cbax=fig.add_axes. Thank you for your help!

Thanks,
Dan

···

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