[Tutor] Importing file data into Python arrays

[Kalle Svensson]

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[Alistair McGowan]
> import array

For the examples you have shown, there is no need to import array.
You are using lists, a basic datatype in Python.

The array module, documented at
http://python.org/doc/current/lib/module-array.html might be of
interest to you anyway, as well as the numeric python extensions at
http://www.pfdubois.com/numpy/ .

> However, when I try to read in data from a file as shown below, I
> end up with the lines, which I can't manipulate.

You will have to manipulate the lines a bit to go from strings to
integers.  How to do this depends on what you want.  If you want a
nested list like
[[1, 2, 3],
 [4, 5, 6],
 [7, 8, 9]]
something like this should work:

arr = []
inp = open ("dat.txt","r")
#read line into array 
for line in inp.readlines():
    # add a new sublist
    arr.append([])
    # loop over the elemets, split by whitespace
    for i in line.split():
        # convert to integer and append to the last
        # element of the list
        arr[-1].append(int(i))

To get a flat list like
[1, 2, 3, 4, 5, 6, 7, 8, 9]
this might do:

arr = []
inp = open ("dat.txt","r")
#read line into array 
for line in inp.readlines():
    # loop over the elemets, split by whitespace
    for i in line.split():
        # convert to integer and append to the list
        arr.append(int(i))

Hope this helps.

Peace,
  Kalle
- -- 
Kalle Svensson, http://www.juckapan.org/~kalle/
Student, root and saint in the Church of Emacs.
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