Financial Modelling in Python

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198 Financial Modelling in Python

range(...)

range([start,] stop[, step]) -> list of integers

Return a list containing an arithmetic progression of integers.

range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults

to 0.

When step is given, it specifies the increment (or decrement).

For example, range(4) returns [0, 1, 2, 3]. The end point is

omitted!

These are exactly the valid indices for a list of 4 elements.

>>>

Now returning to our understanding of the for statement example above:

>>> for i in range(10):

... print i

...

Note how the print i is indented relative to the preceding line (for i in ...). This is

significant. That is, white space is significant in Python and its use indicates where different

parts of statements begin and end much like the use of ‘{’ and ‘}’ in C/C++. To illustrate

further, here’s a more involved snippet:

>>> for i in range(0, 2):

... print i

... for j in range(0, 10):

... print " %d" % (j)

... print

...

0

0

1

2

3

4

5

6

7

8

9

1

0

1

2

3

4

5

6

7

8

9

>>>

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Appendix A: Python 199

Dropping back a level of indentation in line 5 of the above indicated that the print statement

written there was not part of the inner loop body (the inner for statement had reached its