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Xcode – Write file with specific number of columns

I need to write a text document that has a specific number of columns (in this case there are always 16). The way I found to make this happen was: check which is the len of the array (list) where the values I want are and divide by 16, getting the number of rows enough to equate to 16 columns precisely. Surely there is a much more correct way to optimize this process.
Another question I take advantage of to ask is (because I really don’t know how to do it): how to write in 16 columns and always leave with an indentation equivalent to the largest number of that array (i.e.: 8500 = 4 characters = 4 spaces). Something like this:

Example

Here is my code:

f = open('Questions.txt','r')

my_list = [line.split(',')[0]  for line in f]

ff = open('Questions_new.txt','w')

i=0
x=len(my_list)

rows = int(round(len(my_list)//16))

for i in range(rows):
   row = my_list [i::rows]
   ff.write(' '.join(str(x) for x in row)+'n')

The use of line.split is because I am extracting from a text document (example below) all characters of a text document until a comma is found:

1213,4214 12312

13,1231 123

45,343

and he just keeps the information for me:

1213

13

45

If someone could help I would be thankful.

Tags:

2

Answers


  1. 0

    To answer your first question regarding the number of rows, I think your method is quite efficient. An alternative way to structure this includes:

    • Have a while loop which reads in a new value from the text file in every iteration. Inside the while loop, keep a counter for n_rows and n_cols.
      • Write the new value into the output to output[n_rows][n_cols] to right in the current row
      • If n_cols == 16, increment n_row++

    Regarding your second question, you could:

    • do a first pass of reading in all the values, storing them into an array
    • when adding the new value to the array, compare the number of digits against the current max number of digits
    • Copy the values from the array into the output text file, padding up to the max number of digits
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  2. 0

    Here are some lines of code how I would have thought of doing this:

    my_list = [ '12',   '34',    '3467',
            '1234', '34',    '34',
            '123',  '34567', '345',
            '23',   '78'] # your input list
ncolumns = 3 # specify desired number of columns

my_list += [""]*(ncolumns-len(my_list)%ncolumns) # make list multiple of ncolumns
my_list = [my_list[i:i+ncolumns] for i in range(0,len(my_list),ncolumns)] # reshape in rows
rowformat = ("{{:{}}} "*ncolumns).format(*(max(map(len,col)) for col in zip(*my_list))) # format of row text
with open("outputfile.txt","w") as fid:
    fid.write("n".join(rowformat.format(*row) for row in my_list))

    Like with so much in python there are many different ways of achieving the same thing, so the meaning of "Surely there is a much more correct way to optimize this process" has to be specified: do you mean least amount of lines of code? most memory efficient? most readable? Depending on your definition of "correct" your code may be more correct than mine 😉

    In this example the column widths are achieved through string format syntax, see e.g. python-docs. With that you could also easily adjust the alignment of your columns, etcetera.

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