Matplotlib Plot Numpy Matrix As 0 Index

I prepare a numpy matrix then use matplotlib to plot the matrix, such as: >>> import numpy >>> import matplotlib.pylab as plt >>> m = [[0.0, 1.47, 2.43,

Solution 1:

You can use the extent optional parameter to the plt.imshow() function, which is documented here. Like this:

#All the stuff earlier in the program
plt.imshow(matrix, interpolation='nearest', cmap=plt.cm.ocean, extent=(0.5,10.5,0.5,10.5))
plt.colorbar()
plt.show()

For a matrix with an arbitrary shape, you could change this code to something like this:

#All the stuff earlier in the program
plt.imshow(matrix, interpolation='nearest', cmap=plt.cm.ocean,
    extent=(0.5,numpy.shape(matrix)[0]+0.5,0.5,numpy.shape(matrix)[1]+0.5))
plt.colorbar()
plt.show()

This produces a plot that looks like this:

Solution 2:

To get the desired output add these lines after your code, but beforeplt.show():

...
labels = [0, 1, 3, 5, 7, 9]
ax.set_xticklabels(labels)
plt.show()

Note that x-axis and y-axis are in the range [-0.5, 9.5] not int [0, 9]

Edit:

To do it in a more flexible way (in fact, another way of the showed above):

labels = range(0, len(m[0]))
plt.xticks(labels)
plt.show()

Output: