Question

Pylab inserts line breaks where there are nans in the data. How can I get continuous lines. I think matlab does this automatically.

example:

x = linspace(0,1,10)
y = rand(10,2)
y[5:8,1] = nan
plot(x,y,'.-')

I want y[:,1] interpolated but not y[:,0] since there are no points missing.

Answer 1

select the rows without nan

from pylab import isnan
boolind = ~isnan(y).any(1)

then do

plot(x[boolind], y[boolind])

if you want a value from linear interpolation to substitute that nan, you simply record the position of that nan and do the interpolation using adjacent points, but I think for plotting purposes, simply eliminating nan data points is enough – the code will do the linear interpolation for you anyway.

btw: presumably your y = rand((10, 50)) should be y = rand(10, 50), although I am not sure why you wanna plot a 2D array against a 1D.

EDIT

for your particular question, you can simply plot the two columns of y separately

from pylab import *
x = linspace(0,1,10)
y = rand(10,2)
y[5:8,1] = nan
boolind = ~isnan(y)
plot(x[boolind[:,0]],y[boolind[:,0], 0],'.-')
plot(x[boolind[:,1]],y[boolind[:,1], 1],'.-')
show()