[Tutor] How best to create a sharp telemetry log file - from one long string of teletry?

[alan.gauld@bt.com]

Hi Bill,

> Now I'm trying to write a nicely formatted log file out of a single
> string of telemtry that I read of a serial line. 
> The string had 40 different values - numbers such a "120", and titles
> sucs as "OFT" There are 40 of these seperated by white space. 

You don't say whether these come in a predetermined sequence that is
repeatable.
If it is a fixed set then you can use syring slicing to extract the digits:

field1 = strng[4:9]  #or whateve.

Beterr to define these external to the slicing:


# field name    = (start,length)
field1 = (4,5)
field2 = (13,3)
etc...

Then you can slice like:

f1 = strng[field1[0]:field1[0]+field1[1]]
f1 = int(f1)  # if you need them as numbers rather than numeric strings

etc

> place each numerical value into it's own column? 
> 
> I've learned about the string format codes from Alan's book (page 32)
Thats the best solution, just define the line format in terms of field
specifiers:

fmt = "%12s%3d%7d%7s%8.2f\n"

Then in a loop create each line
output.write(headingStrings)  # report header
for lines in buffer:
    getFields()  # assume uses slicing as above
    result = fmt % (f1,f2,f3....)
    output.write(result)

> say for the value of 120.
> 
> '%8.2f' % 120

This will print

"  120.00"

Is that what you want? If its not a floating pint value a %8d might 
be better.

Finally if the string is non deterministic in its numeric content 
you might be better using a regular expression and a findall() 
call to get a list of the strings.

Alan g.
Author of the Learn to Program website
http://www.freenetpages.co.uk/hp/alan.gauld/