range and xrange
The range([start,] stop [,stride]) function constructs a list of integers
a = range(100) # a = [0,1,2,3,4,..., 99]
b = range(10,100) # b = [10,11,12,..., 99]
c = range(10,100,5) # c = [10,15,20,..., 95]
d = range(100,0,-5) # d = [100,95,90,..., 5]
This is commonly used in looping constructs
for i in range(0,100):
statements
But it consumes a lot of memory for large ranges
xrange([start,] stop [,stride]) computes its values
a = xrange(0,1000000000,5)
b = a[198763233]
for i in a:
statements
In general, xrange() is better if looping over many values
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