Outputting appeded list of items into a file

Question

I have a variable,all=[], which stores an appended list of items as follows:

qwe 1qw78 12 qqq ss7 shhs bs77 sghs 7shsb qwe 1qw78 12 qqq ss7 shhs bs77 sghs 7shsb

I tried to ouput the items in a tab-delimited format as 3 columns into a file as follows:

output wanted:

qwe 1qw78 12
qqq ss7 shhs
bs77 sghs 7shsb

I was not exactly sure how to do this, but my attempt is below:

all=[]
with open("file.txt", "r") as input, open("output.txt","w") as outfile:
    for line in input:
    line=line.rstrip()
    all.append(line)        
    for i,item in enumerate(all):
        for i in range(3):
        outfile.write("%s \t" %all)

Any advice will be appreciated.

Thanks

Answer 1

If all is a list the following will work, replacing all with lst:

grouped = (lst[i:i+3] for i in range(0,len(lst),3))

with open("output.txt","w") as f:
    for tup in grouped:
        f.write("\t".join(tup)+"\n")

If each line is as in your question just split each line:

with open("file.txt", "r") as input, open("output.txt","w") as outfile:
for line in input:
    line = line.rstrip().split()
    grouped = (lst[i:i+3] for i in range(0,len(lst),3))
    for tup in grouped:            
        outfile.write("\t".join(tup)+"\n")

If you have a word on each line then modulo and enumerate will do what you want:

with open("input.txt", "r") as inp, open("output.txt","w") as outfile:
    for ind, line in enumerate(inp,1):
        if ind % 3 == 0:
            outfile.write(line.rstrip()+"\n")
        else:
            outfile.write(line.rstrip() + "\t")