Counting non blank and sum of length of lines in python - function

Question

Am trying to create a function that takes a filename and it returns a 2-tuple with the number of the non-empty lines in that program, and the sum of the lengths of all those lines. Here is my current program. I made an attempy and got the following code:
def code_metric(file_name):
with open(file_name) as f:
lines = f.read().splitlines()
char_count = sum(map(len,(map(str.strip,filter(None,lines)))))
return len(lines), char_count
Am supposed to use the functionals map, filter, and reduce for this. I had asked the question previously and improved on my answer but its still giving me an error. Here is the link to the previous version of the question:
Old program code
When I run the file cmtest.py which has the following content
import prompt,math
x = prompt.for_int('Enter x')
print(x,'!=',math.factorial(x),sep='')
the result should be
(3,85)
but I keep getting:
(4,85)
Another file colltaz.py to be tested for example:
the result should be:
(73, 2856)
bit I keep getting:
(59, 2796)
Here is a link to the collatz.py file:
Collatz.py file link
Can anyone help me with correcting the code. Am fairly new to python and any help would be great.

Answer 1

Try this:
def code_metric(file_name):
with open(file_name) as f:
lines = [line.rstrip() for line in f.readlines()]
nonblanklines = [line for line in lines if line]
return len(nonblanklines), sum(len(line) for line in nonblanklines)
Examples:
>>> code_metric('collatz.py')
(73, 2856)
>>> code_metric('cmtest.py')
(3, 85)
Discussion
I was able to achieve the desired result for collatz.py only by removing the trailing newline and trailing blanks off the end of the lines. That is done in this step:
lines = [line.rstrip() for line in f.readlines()]
The next step is to remove the blank lines:
nonblanklines = [line for line in lines if line]
We want to return the number of non-blank lines:
len(nonblanklines)
We also want to return the total number of characters on the non-blank lines:
sum(len(line) for line in nonblanklines)
Alternate Version for Large Files
This version does not require keeping the file in memory all at once:
def code_metric2(file_name):
with open(file_name) as f:
lengths = [len(line) for line in (line.rstrip() for line in f.readlines()) if line]
return len(lengths), sum(lengths)
Alternate Version Using reduce
Python's createor, Guido van Rossum, wrote this about the reduce builtin:
So now reduce(). This is actually the one I've always hated most,
because, apart from a few examples involving + or *, almost every time
I see a reduce() call with a non-trivial function argument, I need to
grab pen and paper to diagram what's actually being fed into that
function before I understand what the reduce() is supposed to do. So
in my mind, the applicability of reduce() is pretty much limited to
associative operators, and in all other cases it's better to write out
the accumulation loop explicitly.
Accordingly reduce is no longer a builtin in python3. For compatibility, though, it remains available in the functools module. The code below how reduce can be used for this particular problem:
from functools import reduce
def code_metric3(file_name):
with open(file_name) as f:
lengths = [len(line) for line in (line.rstrip() for line in f.readlines()) if line]
return len(lengths), reduce(lambda x, y: x+y, lengths)
Here is yet another version which makes heavier use of reduce:
from functools import reduce
def code_metric4(file_name):
def fn(prior, line):
nlines, length = prior
line = line.rstrip()
if line:
nlines += 1
length += len(line)
return nlines, length
with open(file_name) as f:
nlines, length = reduce(fn, f.readlines(), (0, 0))
return nlines, length