Matplotlib plot numpy matrix as 0 index
matplotlib, matrix, numpy, python
Solution
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:
Problem
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, 3.44, 1.08, 2.83, 1.08, 2.13, 2.11, 3.7], [1.47, 0.0, 1.5, 2.39, 2.11, 2.4, 2.11, 1.1, 1.1, 3.21], [2.43, 1.5, 0.0, 1.22, 2.69, 1.33, 3.39, 2.15, 2.12, 1.87], [3.44, 2.39, 1.22, 0.0, 3.45, 2.22, 4.34, 2.54, 3.04, 2.28], [1.08, 2.11, 2.69, 3.45, 0.0, 3.13, 1.76, 2.46, 3.02, 3.85], [2.83, 2.4, 1.33, 2.22, 3.13, 0.0, 3.83, 3.32, 2.73, 0.95], [1.08, 2.11, 3.39, 4.34, 1.76, 3.83, 0.0, 2.47, 2.44, 4.74], [2.13, 1.1, 2.15, 2.54, 2.46, 3.32, 2.47, 0.0, 1.78, 4.01], [2.11, 1.1, 2.12, 3.04, 3.02, 2.73, 2.44, 1.78, 0.0, 3.57], [3.7, 3.21, 1.87, 2.28, 3.85, 0.95, 4.74, 4.01, 3.57, 0.0]] >>> matrix = numpy.matrix(m) >>> matrix matrix([ [ 0. , 1.47, 2.43, 3.44, 1.08, 2.83, 1.08, 2.13, 2.11, 3.7 ], [ 1.47, 0. , 1.5 , 2.39, 2.11, 2.4 , 2.11, 1.1 , 1.1 , 3.21], [ 2.43, 1.5 , 0. , 1.22, 2.69, 1.33, 3.39, 2.15, 2.12, 1.87], [ 3.44, 2.39, 1.22, 0. , 3.45, 2.22, 4.34, 2.54, 3.04, 2.28], [ 1.08, 2.11, 2.69, 3.45, 0. , 3.13, 1.76, 2.46, 3.02, 3.85], [ 2.83, 2.4 , 1.33, 2.22, 3.13, 0. , 3.83, 3.32, 2.73, 0.95], [ 1.08, 2.11, 3.39, 4.34, 1.76, 3.83, 0. , 2.47, 2.44, 4.74], [ 2.13, 1.1 , 2.15, 2.54, 2.46, 3.32, 2.47, 0. , 1.78, 4.01], [ 2.11, 1.1 , 2.12, 3.04, 3.02, 2.73, 2.44, 1.78, 0. , 3.57], [ 3.7 , 3.21, 1.87, 2.28, 3.85, 0.95, 4.74, 4.01, 3.57, 0. ] ]) >>> fig = plt.figure() >>> ax = fig.add_subplot(1,1,1) >>> ax.set_aspect('equal') >>> plt.imshow(matrix, interpolation='nearest', cmap=plt.cm.ocean) >>> plt.colorbar() >>> plt.show() ``` The plot shows like this: This is fine, except for the fact that I would like my axes to go from 1-10, rather than 0-9 (derived from python's 0 indexing) Is there a simple way to do this? Many thanks!!