[Tutor] Importing data from a file.

[Shall, Sydney]

On 21/03/2013 16:17, Alan Gauld wrote:
> On 21/03/13 13:43, Shall, Sydney wrote:
>> I have an elementary question provoked by another post today.
>>
>> 1. Is it the case that ALL imported data from a file is a string?
>
> Assuming you mean data read from a file rather than modules imported 
> using 'import' then the answer is 'it depends'.
>
> Most files are text files and the data is stored as strings and 
> therefore when you read them back they will be strings. You then 
> convert them to the native data using int(), float() etc.
>
> Some files are binary files and then the data read back will be bytes 
> and need to be decoded into the original data. This is often done 
> using the struct module.
>
> Either way if you use the Python read() operation on a file
> you will get back a bunch of bytes. What those bytes represent depends 
> on how they were written. How they are interpreted is down to the 
> programmer.
>
>
>> 2. Does this therefor imply that said data has to be processed
>> appropriately to generate the data in the form required by the program?
>
> Yes, always.
>
>> 3. Are there defined procedures for doing the required processing?
>
> Yes, for the standard types. For custom types and arbitrary binary 
> data you need to find out what the original encoding was and reverse it.
>
> HTH,
>
Thank you Alan, That was most useful.
Cheers,
Sydney

-- 
Professor Sydney Shall,
Department of Haematological Medicine,
King's College London,
Medical School,
123 Coldharbour Lane,
LONDON SE5 9NU,
Tel & Fax: +44 (0)207 848 5902,
E-Mail: sydney.shall,
[correspondents outside the College should add; @kcl.ac.uk]
www.kcl.ac.uk

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