文本文件的元组列表

Question

I have a List consists of String and Number like this:

mylist= [('AGT', 3), ('GTT', 2), ('TTC', 2), ('GTA', 1), ('TAC', 1), ('ACG', 1)]

and want to print to an output file like this

#output.txt
AGT,3
GTT,2
TTC,2
GTA,1
TAC,1
....

I have tried this code

     with open('output.txt', 'w+') as file:
             file.write('\n'.join(map(str, mylist))) #the join function convert the list to string
     return kFreq

and here is the output:

('AGT', 3)
('GTT', 2)
('TTC', 2)
('GTA', 1)
('TAC', 1)
('ACG', 1)

how do I get rid of the ( and ' ' character?

Answer 1

You have to iterate over the tuples and join them into strings. Also you'll need to cast all items to str for that:

print(*(','.join(map(str,i)) for i in mylist), sep='\n')

AGT,3
GTT,2
TTC,2
GTA,1
TAC,1
ACG,1

---

If you want it into a file:

with open("output.txt", "w") as text_file:
    text_file.write('\n'.join([','.join(map(str,i)) for i in mylist]))

Answer 2

For me it looks like task for so-called f-strings . I would do it following way:

mylist= [('AGT', 3), ('GTT', 2), ('TTC', 2), ('GTA', 1), ('TAC', 1), ('ACG', 1)]
output = '\n'.join(f"{x},{y}" for x,y in mylist)
print(output)  # print to stdout for demonstration purposes

Output:

AGT,3
GTT,2
TTC,2
GTA,1
TAC,1
ACG,1

Be warned that this requires Python 3.6 or newer, if you are limited to older version you might use older ways for example .format :

output = '\n'.join("{},{}".format(x,y) for x,y in mylist)

Regardless of your choice, output is ready to be written to file, that is:

with open('output.txt', 'w+') as file:
    file.write(output)