open conditional python files but read data from one

Question

I want to open and read a file depending on a condition, read only if condition met true. I wrote the following scriptlet:

def bb(fname, species):
     if species in ('yeast', 'sc'):
         pm =  open('file.txt', 'rU')
         for line in pm:
             line = line.split()
             with open(fname, 'rU') as user:
                 for e in user:
                     e = e.split()
                     if e[0] in line:
                         print(line)
    elif species in ('human', 'hs'):
         pm =  open('file2.txt', 'rU')
         for line in pm:
             line = line.split()
             with open(fname, 'rU') as user:
                 for e in user:
                     e = e.split()
                     if e[0] in line:
                         print(line)

Is there a proper pythonic way, where I don't have to repeat/write the same lines (line3 to 10) over and over again ? Thanks !

Answer 1

You can put the filename value in a variable

def bb(fname, species):
    if species in ('yeast', 'sc'):
        fname2 = 'file.txt'
    elif species in ('human', 'hs'):
        fname2 = 'file2.txt'
    else:
        raise ValueError("species received illegal value")

    with  open(fname2, 'rU') as pm:
        for line in pm:
            line = line.split()
            with open(fname, 'rU') as user:
                for e in user:
                    e = e.split()
                    if e[0] in line:
                        print(line)

or define another function

def bb(fname, species):
    if species in ('yeast', 'sc'):
        read_file('file.txt', fname)
    elif species in ('human', 'hs'):
        read_file('file2.txt', fname)

def read_file(fname1, fname2):
    with  open(fname1, 'rU') as pm:
        for line in pm:
            line = line.split()
            with open(fname2, 'rU') as user:
                for e in user:
                    e = e.split()
                    if e[0] in line:
                        print(line)

Answer 2

Since you seem to be doing the exact same thing regardless of the condition, you could just collapse everything?

def bb(fname, species):
     if species in ['yeast', 'sc', 'human', 'hs']:
         pm =  open('file.txt', 'rU')
         for line in pm:
             line = line.split()
             with open(fname, 'rU') as user:
                 for e in user:
                     e = e.split()
                     if e[0] in line:
                         print(line)

Either that or you've made a mistake copying the code. If you want to do something different depending on the case, then you could make a function that takes that argument, or do the conditional statement first and use it to set a certain string or value.

Eg

if species in ('yeast', 'sc'):
    permissions = 'rU'

etc.

---

Edit: Ah, with your edited question the answer would be as above but then

if species in ('yeast', 'sc'):
    file_name = 'file.txt'
elif species in ('human', 'hs'):
    file_name = 'file2.txt'

Answer 3

Just put opening of file in if else case rest will be done in a similar manner and same code block as well.

def bb(fname, species):
    if species in ('yeast', 'sc'):
             pm =  open('file.txt', 'rU')
    elif species in ('human', 'hs'):
             pm =  open('file2.txt', 'rU')
         for line in pm:
             line = line.split()
             with open(fname, 'rU') as user:
                 for e in user:
                     e = e.split()
                     if e[0] in line:
                         print(line)