Export data from python to a txt file

[Jason Swails]

On Fri, Mar 29, 2013 at 1:33 PM, Ana Dionísio <anadionisio257 at gmail.com>wrote:

> Hello!!!
>
> I have this lists a=[1,3,5,6,10], b=[a,t,q,r,s] and I need to export it to
> a txt file and I can't use csv.
>

It would help if you showed exactly what you had in your program or in the
Python interpreter.  For instance

a = [1, 3, 5, 6, 10]
b = [a, t, q, r, s]

won't work, since it interprets the letters in the b-list as variables
rather than strings.  It would need to be

b = ['a', 't', 'q', 'r', 's']

or something equivalent.  Assuming you had that part correct:


> And I want the next format:
>
> a 1 3 5 6 10
> b a t q r s
>
> I already have this code:
>
> "f = open("test.txt", 'w')
>  f.write("a")
>  f.write("\n")
>  f.write("b")
>  f.write("\n")
>
>  for i in xrange(len(a)):
>     LDFile.write("\t")
>     LDFile.write(str(a[i]))
>     LDFile.write("\t")
>     LDFile.write(str(b[i]))
>
>  f.close()"
>
> But it doesn't have the format I want. Can you help?
>

Walk through exactly what the computer is doing here.  First it prints a,
then a newline, then b, then a newline:

--begin--
a
b
--end--

Then your for loop executes (notice LDFile and f are different file
objects, so they won't write to the same location).  This will print a tab,
followed by the i'th element of a, followed by another tab, followed by the
i'th element of b.  So this:

a 1 3 5 6 10
b a t q r s

--begin-- [tab]  1 [tab]  a [tab]   3 [tab]   t [tab]   5 [tab]   q [tab]
6 [tab]   r [tab]   10 [tab]   s [tab]--end--

So the final file will look something like this:

a
b
     1     a     3     t     5     q     6     r     10     s


which is obviously not what you want.  The following code will do what you
want (although there are ways of doing this in less code, this is the most
straightforward):

f.write('a\t')
for element in a:
   f.write(str(element) + '\t')
f.write('\n')
f.write('b\t')
for element in b:
   f.write(str(element) + '\t')
f.write('\n')

HTH,
Jason
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