[Tutor] how to read data

[Wayne Werner]

2011/5/7 lina <lina.lastname at gmail.com>

> Hi,
>
> As you will see I am a new beginner of learning python,
>
> I met a problem, hope someone can guide me one or two and help me learn.
> <snip all your data>


Have you tried anything yet? Do you know how to read in from a file? Can you
go over it line by line? There are several tutorials available, such as Alan
Gauld's wonderful tutorial: http://www.alan-g.me.uk/ or the Python
Beginner's Guide has a list of tutorials for both non-programmers and those
with previous experience: http://wiki.python.org/moin/BeginnersGuide

Take a look at those and pay special attention to:

1. File I/0
2. Dictionaries
3. The string.replace method
http://docs.python.org/library/string.html#string.replace
4. String slicing

If I understand what you're asking, you want the large cluster of text at
the end to, instead of having lots of 'n's, have the number after the hash,
correct? i.e. n is #000000, which is 0 in base 10, and the first non-zero
value on that line is #212121 (or 2171169 decimal) so you want something
like this:

0 0 0 0 0 0 0 0 0 0 ... 0 0 2171169 ...

correct?

If so, for something like this I would probably make two files, one
containing the first part ('A c #FFFFFF ...') and another containing the
matrix at the end. The steps I would follow are:

1. Open the "translation" file
2. For each line in the file
    a. Get the character on the line
    b. Get the numeric value the character refers to
    c. Store these values in a way that allows me to use the character to
retrieve the number
3. close the translation file (not strictly necessary, since Python does
this for you when the script finishes, but good practice)
4. open the matrix file and an output file
5. for each line in the matrix
    a. for each character in my translation
        i. replace the characters in the line with the numeric value
followed by a space ( so instead of 0000 you have 0 0 0 0 )
    b. write the line to the output file
6. close the matrix file and the output file (if you don't close the output
file, there may be no data in it!)
7. Go to matlab and do whatever you wanted to.

Since you sound like you're familiar with matlab, just remember that in
Python, arrays start with 0, not 1.

If you get stuck at any of these points, come back and let us know

1. What you tried
2. What you thought should happen
3. What really happened
4. If an error occurred, the full text of any messages you got.

HTH,
Wayne
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