CODEWITHSUNDEEP
pythoncsv
Hana
Hana

Reputation: 1470

Writing out a date format using CSV

I'm reading in a series of CSV files then writing them back out. Some files have different date formats, but I want to write them all out in "%Y-%m-%d" format (YYYY-MM-DD).

How can I write some if statements for the case when the date format is "%m/%d/%Y" and for "%m-%d-%Y" ?

Here's what I've attempted :

reader = csv.reader(gzip.open(readfile), delimiter=',')
for line in reader:
    if datetime.datetime.strptime(line[10], "%m/%d/%Y") == "%m/%d/%Y"
        line[10] = datetime.datetime.strptime(line[26], "%m/%d/%Y").strftime("%Y-%m-%d")
    else:
        line[10] = datetime.datetime.strptime(line[26], "%m-%d-%Y").strftime("%Y-%m-%d")

Upvotes: 0

Views: 105

Answers (2)

buddemat
buddemat

Reputation: 5301

You can use the python dateutil lib. It can do this automatically so that you do not need to write if statements at all.

>>> from dateutil.parser import parse
>>> parse("10/03/2017")
datetime.datetime(2017, 10, 3, 0, 0)
>>> parse("03-12-2010")
datetime.datetime(2010, 3, 12, 0, 0)

This only works if your month always comes first (but this is true for if statements as well). You could also call parse with the option dayfirst=True, if your format were e.g. "%d/%m/%Y", i.e. your day always came first.

Combined with your example this would mean:

from dateutil.parser import parse

for line in reader:
    line[10] = parse(line[26]).strftime("%Y-%m-%d")

(PS: If you are not 100% sure that your line always actually has a valid date string, you should probably include ValueError handling in case parse cannot undestand the string you passed to it.)

Upvotes: 1

Asav Patel
Asav Patel

Reputation: 1162

According to Python's EAFP Philosophy.

If you are certain that your CSV only contains dates in those two formats you can try doing this.

for line in reader:
    try:
        line[10] = datetime.datetime.strptime(line[26], "%m/%d/%Y").strftime("%Y-%m-%d")
    except ValueError:
        line[10] = datetime.datetime.strptime(line[26], "%m-%d-%Y").strftime("%Y-%m-%d")

Upvotes: 1

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