[Numpy-discussion] printing array in tabular form

Sudheer Joseph sudheer.joseph at yahoo.com
Sat May 11 03:55:01 EDT 2013

Thank you Very much,
                         This will help me a lot.
with best regards,

 ----- Original Message -----

> From: Derek Homeier <derek at astro.physik.uni-goettingen.de>
> To: Discussion of Numerical Python <numpy-discussion at scipy.org>
> Cc: 
> Sent: Friday, 10 May 2013 6:10 PM
> Subject: Re: [Numpy-discussion] printing array in tabular form
> On 10.05.2013, at 1:20PM, Sudheer Joseph <sudheer.joseph at yahoo.com> wrote:
>>  If some one has a quick way I would like to learn from them or get a 
> referecence 
>>  where the formatting part is described which was 
>>  my intention while posting here. As I have been using fortran I just tried 
>>  to use it to explain my requirement
> Admittedly the formatting options in Python can be confusing to beginners, 
> precisely
> since they are much more powerful than for many other languages. As already 
> pointed
> out, formats of the type '(5i5)' are very common to Fortran programs and 
> thus readily
> supported by the language. np.savetxt is just a convenience function to support 
> a number
> of similarly common output types, and it can create csv, tab-separated, or 
> plenty of other
> outputs from a numpy array just out of the box. 
> But you added to the confusion as you did not make it clear that you were not 
> just requiring
> a plain csv file as your Fortran example would create (and the first version did 
> not even
> have the commas); since this is a rather non-standard form you will just have to 
> write a
> short loop yourself, wether you are using Fortran or Python.
>>                           Infact the program which should read this file 
> requires it in specified format which should look like
>>  IL = 1,2,3,4,5
>>       1,2,3,4,5
>>       1,2,3,4,5
> The formats are all documented 
> http://docs.python.org/2/library/string.html#format-specification-mini-language
> one important thing to know is that you can pretty much add (i.e. concatenate) 
> them like strings:
> print(("%6s"+4*"%d,"+"%d\n") % (("IL = 
> ",)+tuple(IL[:5])))
> or, perhaps a bit clearer:
> fmt = "%6s"+4*"%d,"+"%d\n"
> print_t = ("IL = ",)+tuple(IL[:5])
> print(fmt % print_t)
> The other important bit to keep in mind is that all arguments have to be passed 
> as tuples.
> This should allow you to write a loop to print with a "header" or an 
> empty header column
> for the subsequent lines as you see fit. 
> Except for the string field which is explicitly formatted "%s" here, 
> this is mostly equivalent
> to the example Henry just posted.
> HTH,
>                     Derek
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