These seems like something very simple, but search as I might I just can't get past it.
I have a CSV file like this:
Day,Event,Value
1,"Rent",500
7,"Wage Payments",1000
I wish to add up all of the numbers in the 'value' column. So far, my code is this:
cr = csv.reader(open("file.csv","rb"))
for row in cr:
print row
#print sum(Value)
How could I go about summing that value?
Thank you.
Considering the first line of csv file is 'Day,Event,Value', you can use a generator expression with sum()
>>> cr = csv.reader(open("file.csv","rb"))
>>> cr.next()
>>> print sum(int(x[2]) for x in cr)
1500
cr.next() line if you don't want to skip the first row in the csv file. That's just there to skip the header row.cr = csv.reader(open("file.csv","rb"))
cr.next() # to skip the header
total = 0
for row in cr:
total += int(row[2])
# possibly do other things with data/rows
print total
There are more terse ways (e.g., list comprehension, or generator expressions) to do this, but this provides the basic idea and also lets you do other things with each line as needed (as pointed out by @MarkRansom too)
int though.
row[2] must be converted to int()cr[1:] throws an error --> TypeError: '_csv.reader' object is not subscriptable.Make a garbage value and read in the first 2 values and "trash" them then when reading in the 3rd value add it to your sum. Don't forget that initially you need to ignore the first 3 values of the file since it will pick up the headers.
Given that 'value' is in column 2, you can perform the following simple for loop:
value_sum=0
for row in cr:
value_sum += row[2]
Or, you can use a comprehension, if you understand it:
value_sum = sum([row[2] for row in cr])
sum(row[2] for row in cr)(although it looks like you will also need a cast to int)
sum(int(row[2]) for row in csv.reader(open("file.csv","rb")) if row[2].isdigit())sum(map(int, zip(*csv.reader(open("file.csv","rb")))[2][1:]))sum(int(row['Value']) for row in csv.DictReader(open("file.csv","rb")))