Question

Hi here is my problem. I have a program that calulcates the averages of data in columns.
Example

Bob
1
2
3

the output is

Bob
2

Some of the data has ‘na’s
So for Joe

Joe
NA
NA
NA

I want this output to be NA

so I wrote an if else loop

The problem is that it doesn’t execute the second part of the loop and just prints out one NA. Any suggestions?

Here is my program:

with open('C://achip.txt', "rtU") as f:
    columns = f.readline().strip().split(" ")
    numRows = 0
    sums = [0] * len(columns)

    numRowsPerColumn = [0] * len(columns) # this figures out the number of columns

    for line in f:
        # Skip empty lines since I was getting that error before
        if not line.strip():
            continue

        values = line.split(" ")
        for i in xrange(len(values)):
            try: # this is the whole strings to math numbers things
                sums[i] += float(values[i])
                numRowsPerColumn[i] += 1
            except ValueError:
                continue 

    with open('c://chipdone.txt', 'w') as ouf:
        for i in xrange(len(columns)):
           if numRowsPerColumn[i] ==0 :
               print 'NA' 
           else:
               print>>ouf, columns[i], sums[i] / numRowsPerColumn[i] # this is the average calculator

The file looks like so:

Joe Bob Sam
1 2 NA
2 4 NA
3 NA NA
1 1  NA

and final output is the names and the averages

Joe Bob Sam 
1.5 1.5 NA

Ok I tried Roger’s suggestion and now I have this error:

Traceback (most recent call last):
File “C:/avy14.py”, line 5, in
for line in f:
ValueError: I/O operation on closed file

Here is this new code:

with open(‘C://achip.txt’, “rtU”) as f:
columns = f.readline().strip().split(” “)
sums = [0] * len(columns)
rows = 0
for line in f:
line = line.strip()
if not line:
continue

rows += 1
for col, v in enumerate(line.split()):
if sums[col] is not None:
if v == “NA”:
sums[col] = None
else:
sums[col] += int(v)

with open(“c:/chipdone.txt”, “w”) as out:
for name, sum in zip(columns, sums):
print >>out, name,
if sum is None:
print >>out, “NA”
else:
print >>out, sum / rows

Answer 1

with open("c:/achip.txt", "rU") as f:
  columns = f.readline().strip().split()
  sums = [0.0] * len(columns)
  row_counts = [0] * len(columns)

  for line in f:
    line = line.strip()
    if not line:
      continue

    for col, v in enumerate(line.split()):
      if v != "NA":
        sums[col] += int(v)
        row_counts[col] += 1

with open("c:/chipdone.txt", "w") as out:
  for name, sum, rows in zip(columns, sums, row_counts):
    print >>out, name,
    if rows == 0:
      print >>out, "NA"
    else:
      print >>out, sum / rows

I’d also use the no-parameter version of split when getting the column names (it allows you to have multiple space separators).

Regarding your edit to include input/output sample, I kept your original format and my output would be:

Joe 1.75
Bob 2.33333333333
Sam NA

This format is 3 rows of (ColumnName, Avg) columns, but you can change the output if you want, of course. 🙂