matplotlib-users

[Matplotlib-users] Adding a colorbar --- how?

[Virgil S. <vs...@it...>]

There are some rather nice and useful matplotlib examples for colormaps 
that are shown at:

http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb

In*Example 1.  Sine wave colored by time (uses the defaults for 
colorline)*, how can one add a colorbar?

--V

Re: [Matplotlib-users] Adding a colorbar --- how?

[Raymond S. <sm...@mi...>]

Hi Virgil,

I did something very much like this recently by simply adding an axes to my
figure and using it to show a linspace of the data range off which the line
color was based. See
http://matplotlib.org/examples/color/colormaps_reference.html.

Best,
Ray


On Sun, Jun 15, 2014 at 6:17 PM, Virgil Stokes <vs...@it...> wrote:

>  There are some rather nice and useful matplotlib examples for colormaps
> that are shown at:
>
>
> http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
>
> In* Example 1.  Sine wave colored by time (uses the defaults for
> colorline)*, how can one add a colorbar?
>
> --V
>
>
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Re: [Matplotlib-users] Adding a colorbar --- how?

[Virgil S. <vs...@it...>]

On 16-Jun-14 00:46, Raymond Smith wrote:
> Hi Virgil,
>
> I did something very much like this recently by simply adding an axes 
> to my figure and using it to show a linspace of the data range off 
> which the line color was based. See 
> http://matplotlib.org/examples/color/colormaps_reference.html.
>
> Best,
> Ray
>
>
> On Sun, Jun 15, 2014 at 6:17 PM, Virgil Stokes <vs...@it... 
> <mailto:vs...@it...>> wrote:
>
>     There are some rather nice and useful matplotlib examples for
>     colormaps that are shown at:
>
>     http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
>
>     In*Example 1.  Sine wave colored by time (uses the defaults for
>     colorline)*, how can one add a colorbar?
>
>     --V
>
>     ------------------------------------------------------------------------------
>     HPCC Systems Open Source Big Data Platform from LexisNexis Risk
>     Solutions
>     Find What Matters Most in Your Big Data with HPCC Systems
>     Open Source. Fast. Scalable. Simple. Ideal for Dirty Data.
>     Leverages Graph Analysis for Fast Processing & Easy Data Exploration
>     http://p.sf.net/sfu/hpccsystems
>     _______________________________________________
>     Matplotlib-users mailing list
>     Mat...@li...
>     <mailto:Mat...@li...>
>     https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
Thanks for your response to my request, Ray. I had looked at this 
approach earlier; but, what I really need is something like is produced 
by the following code for the cax object:

"""Produce custom labelling for a colorbar.

  Original Script:  Scott Sinclair
     Modification:  V. Stokes
"""

import matplotlib.pyplot as plt
import numpy             as np
import matplotlib.colors as col
from matplotlib   import cm
from numpy.random import randn

def register_cmap():
     """
      Purpose: define colormap using the from_List() method as a
               segmented list and register it.
     """
     cmap_Name  = 'reyegr'    # my colormap name
     startcolor = '#00AF33'   # truegreen
     midcolor   = '#FFE600'   # yolk (a medium dark yellow)
     endcolor   = '#FF0033'   # bright red
     cmap2 = col.LinearSegmentedColormap.from_list(cmap_Name,
[startcolor,midcolor,endcolor])
     cm.register_cmap(cmap=cmap2)
     return cm.get_cmap(cmap_Name)  # my new cmap for 'reylgr'

#-----------------------------------------------------------------------------
my_cmap = register_cmap()

## Vertical colorbar-1
fig, ax = plt.subplots()

data = np.clip(randn(250, 250), -1, 1)

cax = ax.imshow(data, interpolation='nearest', cmap=my_cmap)
ax.set_title('Gaussian noise with vertical colorbar')
# Add colorbar, make sure to specify tick locations to match desired 
ticklabels
cbar = fig.colorbar(cax, ticks=[-1, 0, 1])
cbar.ax.set_yticklabels(['<-1', '0', '> 1'])# vertically oriented colorbar

## Vertical colorbar-2
fig, ax = plt.subplots()

data = np.clip(randn(50, 50), -1, 1)

#cax = ax.imshow(data, interpolation='nearest', cmap=cm.coolwarm)
cax = ax.imshow(data, interpolation='nearest', cmap=my_cmap)
ax.set_title('Gaussian noise with vertical colorbar')

# Add colorbar, make sure to specify tick locations to match desired 
ticklabels
cbar = fig.colorbar(cax, ticks=[-1, 0, 1])
# Vertically oriented (by default) colorbar
cbar.ax.set_yticklabels(['Low', 'Medium', 'High'])

## Horizontal colorbar
fig, ax = plt.subplots()
#
cax = ax.imshow(data, interpolation='nearest', cmap=my_cmap)
ax.set_title('Gaussian noise with horizontal colorbar')

cbar = fig.colorbar(cax, ticks=[-1, 0, 1], orientation='horizontal')
cbar.ax.set_xticklabels(['Low', 'Medium', 'High'])# horizontal colorbar

plt.show()

But, for a colorline object, which was referenced in the link given in 
my earlier email.

--V

Re: [Matplotlib-users] Adding a colorbar --- how?

[Eric F. <ef...@ha...>]

On 2014/06/15, 12:17 PM, Virgil Stokes wrote:
> There are some rather nice and useful matplotlib examples for colormaps
> that are shown at:
>
> http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
>
> In*Example 1.  Sine wave colored by time (uses the defaults for
> colorline)*, how can one add a colorbar?

lc = colorline(x, y)
cbar = fig.colorbar(lc)

Eric



>
> --V
>
>
> ------------------------------------------------------------------------------
> HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions
> Find What Matters Most in Your Big Data with HPCC Systems
> Open Source. Fast. Scalable. Simple. Ideal for Dirty Data.
> Leverages Graph Analysis for Fast Processing & Easy Data Exploration
> http://p.sf.net/sfu/hpccsystems
>
>
>
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>

Re: [Matplotlib-users] Adding a colorbar --- how?

[Virgil S. <vs...@it...>]

On 16-Jun-14 01:12, Eric Firing wrote:
> On 2014/06/15, 12:17 PM, Virgil Stokes wrote:
>> There are some rather nice and useful matplotlib examples for colormaps
>> that are shown at:
>>
>> http://nbviewer.ipython.org/github/dpsanders/matplotlib-examples/blob/master/colorline.ipynb
>>
>> In*Example 1.  Sine wave colored by time (uses the defaults for
>> colorline)*, how can one add a colorbar?
> lc = colorline(x, y)
> cbar = fig.colorbar(lc)
>
> Eric
>
>
This works fine --- thanks very much Eric.

Have a good day