How to count the occurrences of a string in a number of string pairs in python? [closed]

I have two textfiles here. I want to count the number of occurrences of strings in “Textfile 1” among the string pairs given in “Textfile 2”.

Textfile_1:

1763_0M73
2610_0M63
7529_12M64
7529_18M64
0091_00M56

Textfile_2:

1763_0M73, 2610_0M63
2610_0M63, 7529_12M64
7529_18M64, 0091_00M56
0091_00M56, 7529_12M64
0267_12M64, 0091_00M56

Expected Output:

1763_0M73, 1
2610_0M63, 2
7529_12M64, 2
7529_18M64, 1
0091_00M56, 3

I tried the following script. But it is not giving the expected output.

with open('Textfile_2.txt') as f1:
    lookup = dict([x.strip() for x in line.split(',')] for line in f1)
print(lookup)

with open('Output.txt', 'w') as out:
    with open('Textfile_1.txt') as f2:
        for line in f2:
            k = line.strip()
            n = lookup[k]
            print(n)

Does anybody know how to do this in python? I’m quite new to python programming.

Answer

A few things not done correctly in your code. Here’s the list comprehension code.

#Step 1: Read the Textfile_1 and store them as dictionary values
#strip out the n as you read through each record from the file
#value of each element will be set to 0
with open('Textfile_1.txt','r') as f1:
    txt1 = {_.rstrip("n"):0 for _ in f1}

#Step 2: Read the Textfile_2 and strip out the n. This will give you two values
#Then split the values into a list. You will get [[str1,str2],[str3,str4]...]
with open('Textfile_2.txt','r') as f2:
    txt2 = [z.rstrip("n").split(',') for z in f2]

#Step 3: The strings in the list of lists may have leading or trailing spaces
#as you iterate thru them, remove the leading/trailing spaces
#then check for that value in the dictionary
#if found, increment the value by 1
for i in [y.strip() for x in txt2 for y in x]:
    if i in txt1: txt1[i] += 1

#Step 4: print the final dictionary as it now containts the counts 
print (txt1)


#Step 5: If you want to write this into a file, then use the below code
#Open file in write mode. Iterate thru the dictionary using txt1.items()
#for each key and value, write to file. Include n to have a newline
with open('Textfile_3.txt','w') as f3:
    for k,v in txt1.items():
        t3 = k + ', ' + str(v) + 'n'
        f3.write(t3)

The output of this is:

{'1763_0M73': 0, '2610_0M63': 0, '7529_12M64': 2, '7529_18M64': 1, '0091_00M56': 3}

The output to Textfile_3 will be:

1763_00M73, 1
2610_00M63, 2
7529_12M64, 2
7529_18M64, 1
0091_00M56, 3