How to place an image colorbar next to the image when there are several subplots ?

Community matplotlib-users
1

Peter,

You鈥檙e welcome.

While I appreciate that you are trying to cut down on unnecessary emails (as per emailcharter.org - interesting read), it is appropriate to include the list in your responses, especially one indicating that a solution has been found, so that others on the list stop thinking about how they could help, and so that a person reading the archived list messages can feel confident that the suggestions were worthwhile. :slight_smile: NNTR

-Sterling

路路路

On Feb 20, 2015, at 3:20PM, Peter Rowat <peter@...4612...> wrote:

Thank you both for your help, my problem is solved. You both had similar suggestions, and now I have a slightly better understanding of matplotlib.

Peter
Save our in-boxes! http://emailcharter.org

On Feb 20, 2015, at 12:48 AM, Fabrice Silva <silva@...1918...> wrote:

Le jeudi 19 f茅vrier 2015 脿 23:10 -0800, Peter Rowat a 茅crit :

I apologize for asking such a trivial question, but I鈥檝e spent a long time trying to fix this:

I have a large 2D array that displays as an image, with a colorbar on the side.
I also display 2 curves on top of the image. i.e. in same axes.
The following code does it:

   fig,ax = plt.subplots()
   cax = ax.imshow(bighistT, extent=myextent, cmap = cm.coolwarm, aspect = myaspect,\
       interpolation='nearest')
   ax.set_title("Dummy title")
   # Add colorbar
   cbar = fig.colorbar(cax)
   ax.set_ylabel('mV')

   ax.plot(emtrate, emrate, '.r') #curve 1
   ax.plot(tt, rate*50 - 25.0, '-k', linewidth=3) #curve 2

   plt.show()

IN FACT,
I want the curves in separate axes, below the image while the colorbar remains immediately to the right
of the image.

I've tried many minor variations, for way over an hour..
I've looked at demos, read about colorbar in several different parts of matplotlib docs...

Can someone help?? .... Either the colorbar is next to the last plot, or else I
get an error.

Here is code that I've tried: It puts the colorbar in the wrong place, and in addition the image size
is very small while the ax2 and ax3 curve plots are much wider.
I want the image and the second 2 plots the same width.

   fig, (ax1, ax2,ax3) = plt.subplots(3,1)
   cax = ax1.imshow(bighistT, extent=myextent, cmap = cm.coolwarm, aspect = myaspect,\
       interpolation='nearest')
   ax1.set_title("Dummy title")
   # Add colorbar
# cbar = fig.colorbar(cax) # this places the colorbar next to the third subplot
   plt.colorbar(cax) # so does this

cax is not the Axes containing the image, but the image itself. It seems
that you want to "steal" some space to the first subplot so:

       fig, (ax1, ax2,ax3) = plt.subplots(3,1)
       im = ax1.imshow(bighistT, extent=myextent, cmap=cm.coolwarm,
           aspect=myaspect, interpolation='nearest')
       ax1.set_title("Dummy title")
       cbar = fig.colorbar(im, ax=ax1)

or you can also create a new Axes between ax1 and ax2, and tell
colorbar() to put the Colorbar into (with the cax keyword argument)

See
http://matplotlib.org/api/figure_api.html#matplotlib.figure.Figure.colorbar

--
Fabrice

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