Question

Whenever I generate an image it very easy to zoom it manually using pylab, i.e. drawing a rectangle around the region we intend to zoom in. I was wondering if it was possible coding this operation.

Here is an example code, where I generate a 100×100 image with random values on each row:

from random import *
from pylab import *
from numpy import *


a=ones((100,100))
image=array([dummy*random() for dummy in a])

imshow(image,extent=[0,1]+[5,6])

In the above example our image extends from 0 to 1 in the x-axis and from 5 to 6 in the y-axis. How can show a zoom on the image, let’s say in the region 0.5

Answer 1

You can use scipy.ndimage.interpolation.zoom() to resize array.

Edit:

Sorry, I misunstand your question. You can use xlim() and ylim() to set the range of X and Y axis:

import numpy as np
import pylab as pl

y, x = np.ogrid[-1:1:100j, -1:1:100j]
z = np.sin(4*(x**2+y**2))

pl.imshow(z, origin="lower", extent=(-1,1,-1,1))
pl.xlim(-0.5, 0)
pl.ylim(0.5, 1.0)
pl.show()