Example for babe

zeroing.py

# Make up some data in nested lists 
strain_data = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]

# To make things a bit more readable, let's define a function that operates
# on a single list...
def zero(data):
    """Returns the difference between the items in "data" and its first item.""" 
    # This is a "list comprehension". It's basically a 1-line for loop
    return [item - data[0] for item in data]

# Now, we'll apply "zero" to all of the lists in "strain_data"...
strain_data = [zero(item) for item in strain_data]

# And have a look at the result...
print strain_data