Even kernel size (#66)

* Warn even kernel size instead of halting

Wouldn't it be more friendly if BioSPPy solved for the user the issue of passing an even kernel size when median filtering? Because raising an error halts the program, which isn't necessary since it's not problematic. Here's a proposal to solve the issue and alert the user.

* Update warnings

---------

Co-authored-by: João Saraiva <[email protected]>

Author: sofia3ms

biosppy/signals/tools.py

@@ -16,6 +16,9 @@
 from six.moves import range
 import six
 
+# built-in
+import warnings
+
 # 3rd party
 import sys
 import numpy as np
@@ -592,7 +595,8 @@ def smoother(signal=None, kernel="boxzen", size=10, mirror=True, **kwargs):
         elif kernel == "median":
             # median filter
             if size % 2 == 0:
-                raise ValueError("When the kernel is 'median', size must be odd.")
+                size -= 1
+                warnings.warn("When the kernel is 'median', size must be odd, so the size was decremented by one.")
 
             smoothed = ss.medfilt(signal, kernel_size=size)