Can anyone help me understand this: the code below produces a plot in
which the x and y axis labels are reversed relative to the direction in
which z varies on the plot, although the gradient arrows are correctly
oriented. Is there something I've missed in understanding the sense of
the x and y directions in mgrid, imshow, and gradient?
"""
x,y axes seem to be reversed
"""
import numpy as np
from matplotlib.pylab import *
dx = .25; dy = .25
xlen = 2.0; ylen = 2.0
x,y = np.mgrid[-xlen:xlen:dx, -ylen:ylen:dy] #also works with ogrid
z = x
hold(True)
imshow(z, origin='lower', extent=[-xlen,xlen,-ylen,ylen])
colorbar()
[u,v] = np.gradient(z)
u /= dx; v /= dy
QP = quiver(x,y,u,v,pivot='middle',color=[0.5,0.5,0.5])
quiverkey(QP, 0.85, 1.05, 1.0, '1 unit', labelpos='N')
xlabel('x')
ylabel('y')
title('slope')
show()
------------------------------------------------------------------------------
Index, Search & Analyze Logs and other IT data in Real-Time with Splunk
Collect, index and harness all the fast moving IT data generated by your
applications, servers and devices whether physical, virtual or in the cloud.
Deliver compliance at lower cost and gain new business insights.
Free Software Download: http://p.sf.net/sfu/splunk-dev2dev
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
