matplotlib-users Mailing List for matplotlib

2011/4/23 _olivier_ <ol...@gm...>:
> [...]

> I have got a matrix 6x500 (so one size is much biggger than the other one)
> and I try to expand the shorter axe so that the labels on it are well
> displayed (not overlapped.

Use the aspect kwarg in matshow.

Goyo

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receive it twice...

Hello,

This question has certainly been answered in a previous thread but after
searching around I did not find any solution...

I have got a matrix 6x500 (so one size is much biggger than the other one)
and I try to expand the shorter axe so that the labels on it are well
displayed (not overlapped.

I am googling/searching on the documentation about subplots_adjust, ... but
did not find any solution.

Here is the code that present the problem I have.

Thanks in advance for any help.  Olivier

import numpy as np
from matplotlib.pylab import *
import matplotlib.pyplot as plt

sizeX = 6
sizeY = 500

xlabels = []
ylabels = []

for i in range ( 0, sizeX ):
  xlabels.append( str( i ) )

for i in range ( 0, sizeY ):
  ylabels.append( str( i ) )

dims = ( sizeX, sizeY )

data = zeros( dims )
for i in range( 0, sizeX ):
  for j in range( 0, sizeY ):
    data[ i, j ] = np.random.rand()

figure = plt.figure()
axes = figure.add_subplot( 111 )
cax = axes.matshow( data, interpolation = 'nearest' )
col = figure.colorbar( cax )

plt.show()
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2011/4/23 jfortiv <jf...@gm...>:
>
> Hi,
>
> This actually did not work for me.  Can you show me the full code that you
> used to successfully produce the time-format x-axis labels?

See attached files.

Goyo

Hi,

This actually did not work for me.  Can you show me the full code that you
used to successfully produce the time-format x-axis labels?

Thanks,
James


Sebastian Berg wrote:
> 
> Hello,
> 
> don't know the foo behind it, but using
> ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m-%d %H:%M:%S'))
> works.
> 
> Regards,
> 
> Sebastian
> 
> On Sun, 2011-04-17 at 19:52 -0700, jfortiv wrote:
> 
>> Hello, 
>> 
>> I'm trying to create a bar chart that looks something like a gannt
>> chart...
>> 
>> See the simple example here:
>> 
>> http://www.promana.net/making-use-of-gantt-charts/
>> 
>> I'm trying to utilize barh() and fmt_xdata to accomplish this with the
>> following:
>> 
>> #~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> date1 = datetime.datetime( 2000, 3, 2)
>> date2 = datetime.datetime( 2000, 3, 6)
>> delta = datetime.timedelta(hours=6)
>> dates = mdates.drange(date1, date2, delta)
>> 
>> val = mdates.drange(date1,date2,delta)   # the bar lengths
>> pos = range(len(val))    # the bar centers on the y axis
>> height=0.5        # the bar height
>> left=mdates.drange(date1,date2,delta)        # the bar starting position
>> 
>> fig = plt.figure()
>> ax = fig.add_subplot(111)
>> ax.barh(pos,val,height=height,left=left,align='center',alpha=0.3)
>> ax.fmt_xdata = mdates.DateFormatter('%Y-%m-%d %H:%M:%S')
>> 
>> #~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> 
>> Even with ax.fmt_xdata, I'm simply getting numbers on the x-axis instead
>> of
>> dates.  Can anyone offer some pointers?
>> 
>> Thanks,
>> James
> 
> 
> 
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Hi Xavier,

Xavier Gnata, on 2011-04-23 02:33,  wrote:
> Imagine you have this code:
> 
> import  numpy  as  np
> import  matplotlib.cm  as  cm
> import  matplotlib.mlab  as  mlab
> import  matplotlib.pyplot  as  plt
> 
> delta  =  0.25
> x  =  y  =  np.arange(-3.0,  3.0,  delta)
> X,  Y  =  np.meshgrid(x,  y)
> Z1  =  mlab.bivariate_normal(X,  Y,  1.0,  1.0,  0.0,  0.0)
> Z2  =  mlab.bivariate_normal(X,  Y,  1.5,  0.5,  1,  1)
> Z  =  Z2-Z1   # difference of Gaussians
> 
> plt.imshow(Z,  interpolation='nearest',  cmap=cm.gray,  origin='lower',  extent=[-3,3,-3,3])

> Then you want to change the color of a few pixels to red.
> You have a list of coordinates (i,j) and each pixel in this list should 
> now be red.
> 
> I could play with masked arrays like in:
> http://matplotlib.sourceforge.net/examples/pylab_examples/image_masked.html
> but I would prefer a simple "display this pixel (i,j) in red whatever 
> his value is" function.

Since you're using a gray color map for that image, you won't be
able to set a particular pixel to red. You'll have to either
overlay a new image that would be masked out everywhere except
for the pixels you want to change, as you mentioned, or create
new image patches at the corresponding positions like this:

  idx2im = lambda i,j: (x[i],x[j+1],y[i],y[j+1] )
  plt.imshow([[.9]], extent=idx2im(12,12), cmap =cm.jet, origin='lower',vmin=0,vmax=1)

or something like this:

  plt.Rectangle((x[10],y[10]),width=delta,height=delta,color='red')
  ax = plt.gca()
  ax.add_artist(r)
  plt.draw()


best,
-- 
Paul Ivanov
314 address only used for lists,  off-list direct email at:
http://pirsquared.org | GPG/PGP key id: 0x0F3E28F7 

Hi,

Imagine you have this code:

import  numpy  as  np
import  matplotlib.cm  as  cm
import  matplotlib.mlab  as  mlab
import  matplotlib.pyplot  as  plt

delta  =  0.25
x  =  y  =  np.arange(-3.0,  3.0,  delta)
X,  Y  =  np.meshgrid(x,  y)
Z1  =  mlab.bivariate_normal(X,  Y,  1.0,  1.0,  0.0,  0.0)
Z2  =  mlab.bivariate_normal(X,  Y,  1.5,  0.5,  1,  1)
Z  =  Z2-Z1   # difference of Gaussians

plt.imshow(Z,  interpolation='nearest',  cmap=cm.gray,  origin='lower',  extent=[-3,3,-3,3])

Then you want to change the color of a few pixels to red.
You have a list of coordinates (i,j) and each pixel in this list should 
now be red.

I could play with masked arrays like in:
http://matplotlib.sourceforge.net/examples/pylab_examples/image_masked.html
but I would prefer a simple "display this pixel (i,j) in red whatever 
his value is" function.

Xavier