Relationships between objects AxonIO example on Python 3.6/neo 0.5.0alpha1: Extracting magnitudes

[msuzen]

This is a version of the AxonIO example from documentation which is tested with Python 3.6. This could be useful for people new to library and using Python 3. It shows how to access neo object's data components, particularly extracting raw magnitudes.

import neo
neo.__version__ # tested on 0.5.0alpha1  with Py3.6
from neo.io import AxonIO
import urllib
from matplotlib import pyplot as plt
url      = "https://portal.g-node.org/neo/axon/File_axon_3.abf"
filename = './test.abf'
urllib.request.urlretrieve(url, filename)
r        = AxonIO(filename=filename)
# Get the first block
bl       = r.read()[0]                      
is_block = isinstance(bl, neo.core.block.Block) # Is this a neo block?
# Extract analog signals from the first segment
ans = bl.segments[0].analogsignals # There are two signals
t  = ans[0].times.magnitude                
s1 = ans[0] # Signal 1
s2 = ans[1] # Signal 2

# Now plot analog signal        
plt.plot(t, s1.magnitude, label=s1.name)
plt.plot(t, s2.magnitude, label=s2.name)
plt.legend(loc="upperright")
xunit = str(s1.times.units)
yunit = str(s1.units)
plt.xlabel("Time" + "(" + xunit +  ")")
plt.ylabel("Analog Signal" + "(" + yunit +  ")")
plt.show()

Note: Thanks to @achilleas-k for magnitude tip.