CODEWITHSUNDEEP
pythongraphmatplotlibplot
erthy
erthy

Reputation: 81

Matplotlib/Pylab - part of plot disappears after setting log scale

I have a small code producing the following picture with this code:

Code 1:

hist, rhist = np.histogram(r, bins=40, range=(0, 0.25))
hist = -hist/np.trapz(rhist[:-1],hist)
plt.plot(rhist[:-1], hist)

Output of code 1: enter image description here

Then I try setting the plot to have a logarithmic Y axis so that I can recognise small peaks more clearly. This is the result.

Code 2:

hist, rhist = np.histogram(r, bins=40, range=(0, 0.25))
hist = -hist/np.trapz(rhist[:-1],hist)
plt.semilogy(rhist[:-1], hist)

Output of code 2: enter image description here

As you can see, part of my plot disappears. There are 40 bins, I can however only count about 15 in the new plot. Any help will be greatly appreciated. I am using Enthought Canopy of the latest version for academic use. E.

UPDATE: I did find a similar question here, old, dead and unanswered though.

Upvotes: 2

Views: 1255

Answers (3)

esmit
esmit

Reputation: 1797

Issue plt.yscale('symlog') at the end of your plotting. See here for a description of 'symlog'.

Upvotes: 1

user2304916
user2304916

Reputation: 8124

A common visual trick to "display" zero in log scale is to use a very small value instead:

plt.semilogy(rhist[:-1], hist+1e-6)

In this case beaware of correct interpretation of plot though.

Upvotes: 0

will
will

Reputation: 10650

I'm pretty sure it's just not plotting those values because they are zero.

Log(0) = -Infinity.

Plotting that is going to make your graph look pretty rubbish...

Upvotes: 1

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