How to plot 2D matrix whose data is not equally spaced along x-axis using Python?

Question

I am trying to plot a 2D matrix using the matplotlib library (the only one I know so far). However, the function matplotlib.pyplot.imshow(matrix) presumes that the data is equally spaced along each axis while the data I want to plot is not. My data looks like: the first column of matrix is data on line x=0, the second column's data is on line x=1.27 instead of x=1, and data of third column is on line x=1.42 but not x=2 and so on.

BTW, data is equally spaced along y-axis.

So I'm wondering if there is anyway I can plot this in the way I hope? Thank you for your time and kind help in advance!

------ newbee in Programming

update: First of all, thank you all for your suggestions! I have tried the methods and here are the outputs:

This is the graph plotted by contourf which is not as I expected. pcolormesh doesn't not give an ideal output either. What I am trying to plot is data of seismic traces which represents the underground structure. I hope to plot something like this:

If there's any advice on how I can do that, please give me a hint! Thank you very much!

Answer 1

I would suggest you to use the function pcolormesh .

You just need to enter the the intervals defined in the 1D arrays x, y and the 2D data, accordingly. Below you find a simple example.

from pylab import *
x = logspace(log10(1),log10(100),11)
y = linspace(1,100,21)

data = rand(20,10)
pcolormesh(x,y,data)
show()

Notice that x and y have an extra point. In this case, data fills up the intervals defined by x and y. Otherwise, you can use the function contourf .

Cheers

Answer 2

You want filled contours ...

• confourf demo
• matplotlib.pyplot.contourf docs

The examples should help you get started. Let us know if you have specific problems.