PYTHONEEG ANALYSIS EXAMPLE

FROM

THINK PYTHON

HOW TO THINK LIKE A COMPUTER SCIENTIST

EEG DATA COLLECTION

THEIR TEST BENCH

GENERATES A CSV FILELOOKS LIKE THE FOLLOWING IN EXCEL

Channelssample number

LOOKING AT IT IN NOTEPAD++

Suppose we just want channel 2 and none of the other data. We will use Python to extract that column only.Once it is extracted we can graph it.

OPEN THE FILE AND READ IT.

File=open("eegdata.csv",'r')

File.readline(); # Get rid of the first line.

# It contains only header data

for line in File:

print line

# The above should open the file and print it out one line at a time.

# As soon as this works we can then process each line

REMEMBER SPLIT? If we have a string (or line) that is a CSV string we can split it into pieces and place the result into a list.

Example : str = “34,23,65,77,12”

a = str.split(‘,’)

print a

['34', '23', '65', '77', '12']

But these are strings in a list and not numbers. So.

a[2] is ‘65’ . Can we convert this guy to a float?

float(a[2]) is now 65 Capice?!

THE SCRIPT

File=open("eegdata.csv",'r')

File.readline();

channel = []

for line in File:

list=line.split(',')

channel.append(float(list[2]))

print channel

plot (channel[0:128)) # only plot the first 128 samples

WHAT ABOUT MULTIPLE GRAPHSFile=open("eegdata.csv",'r')

File.readline();

channel = []

for line in File:

list=line.split(',')

channel.append(float(list[2]))

print channel

figure(1)

plot(channel[:128])

figure(2)

plot(channel[128:256])