Alan Harris-Reid Alan Harris-Reid - 1 year ago 115
Python Question

Number of lines in csv.DictReader

I have a csv DictReader object (using Python 3.1), but I would like to know the number of lines/rows contained in the reader before I iterate through it. Something like as follows...

myreader = csv.DictReader(open('myFile.csv', newline=''))

totalrows = ?

rowcount = 0
for row in myreader:
rowcount +=1
print("Row %d/%d" % (rowcount,totalrows))

I know I could get the total by iterating through the reader, but then I couldn't run the 'for' loop. I could iterate through a copy of the reader, but I cannot find how to copy an iterator.

I could also use

totalrows = len(open('myFile.csv').readlines())

but that seems an unnecessary re-opening of the file. I would rather get the count from the DictReader if possible.

Any help would be appreciated.


Answer Source
rows = list(myreader)
totalrows = len(rows)
for i, row in enumerate(rows):
    print("Row %d/%d" % (i+1, totalrows))
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