EMD's max_imf doesn't return the expected number of IMFs

Describe the bug From the documentation, the ``EMD.emd()method is supposed to returnmax_imf` number of IMFs

The decomposition is limited to *max_imf* imfs.

However, it returns that number + 1.

To Reproduce

from PyEMD import EMD
import numpy as np
s = np.random.random(100)

emd = EMD()
IMFs = emd(s, max_imf=3)

assert len(IMFs) == 3

Expected behavior Either return the appropriate number of IMFs or adjust the documentation.

[laszukdawid]

Hey @kritchie, I think the confusion is from distinguishing what is an IMF (Intrinsic Mode Function). I had a long chat initially with folks who were using this package (and also for own research). The conclusion was to extract IMFs and then any remaining is added as the residue. In such a case, if you set max_imf=3 you’ll get at least 3 signals and sometimes 4 - the last being residue. If you prefer, you can also use emd.get_imfs_and_residue method which returns tuple of (imfs, residue).

Hope this helps, Dawid

[laszukdawid]

Added info with commit 7ebc39eb449b234e401d006266430a62de2db0c5