[Matplotlib-users] imshow and pcolor differences

[Richard M. <rg...@as...>]

Hello,

I want to display some data as an image and also as a contour.

I have been looking at imshow and pcolor and find that contour
and imshow are behaving differently than pcolor. In the example below I
have a 5x5 image. pshow displays the pixels but imshow and contour shows
resampling artifacts since they resample offset by 0.5pixels.

The advantage of imshow is that the pixels are square which is what I
want. I also want to use contour which also seems to show the same
type of resampling as imshow.

import numpy as np
import matplotlib as mpl
import matplotlib.pyplot as plt

image = np.random.rand(5,5)

plt.figure()
plt.pcolor(image)
plt.title('pcolor defaults')

plt.figure()
plt.imshow(image, origin='lower')
plt.title('imshow defaults with origin=lower')

plt.show()

Is there a method to force imshow to not resample the image
It is not obvius to me from reading the help for imshow and pcolor.


Thanks, richard

-------------------------------------------------------------------
 Dr. Richard G. McMahon    | Phone (office)     44-(0)-1223-337519
 University of Cambridge   |       (switchboard)       1223-337548
 Institute of Astronomy    |       (secretary)         1223-337516
 Madingley Rd              | FAX                       1223-337523
 Cambridge, CB3 OHA, UK.   | mobile                    7885-409019
 Office: Hoyle 18          | home                      1223-359770
-------------------------------------------------------------------
 email: rg...@as...  | WWW:    http://www.ast.cam.ac.uk/~rgm
 ric...@gm... | skype:                richardgmcmahon
-------------------------------------------------------------------