What's wrong with this code for sorting csv file according to date?

Question

I have this csv file which look like this:

datetime_period,value
01 Apr 2021 00:00,92.85
01 Apr 2021 00:30,91.73
11 Feb 2021 19:30,88.58
11 Feb 2021 20:00,88.58
13 Jan 2021 13:00,80.49
13 Jan 2021 13:30,81.95

I want to sort this csv according to the datetime in column datetime_period.

I used this link Sorting a csv object by dates in python as a guide.

Here is my code;

data = csv.reader(open(csv_file_path, 'r'))
data = sorted(data, key=lambda row: datetime.strptime(row[0], "%d %b %Y %H:%M"))

I get the error:

ValueError: time data 'time_period' does not match format '%d %b %Y %H:%M'
python-BaseException

I looked at the code and think my code does match the datetime format. Can someone tell me what is wrong with the code or provide an alternative solution?

I am using python 3.8.5

Answer 1

You're trying to sort your header line, which does not contain datetime values.

A way around this is to pop off the headers prior to sorting, and add them back after.

data = [line for line in csv.reader(open('test.csv', 'r'))]

headers = data.pop(0)

data = sorted(data, key=lambda row: datetime.strptime(row[0], "%d %b %Y %H:%M"))
#[['13 Jan 2021 13:00', '80.49'], ['13 Jan 2021 13:30', '81.95'], ['11 Feb 2021 19:30', '88.58'], ['11 Feb 2021 20:00', '88.58'], ['01 Apr 2021 00:00', '92.85'], ['01 Apr 2021 00:30', '91.73']]

out = [headers] + data

#[['datetime_period', 'value'], ['13 Jan 2021 13:00', '80.49'], ['13 Jan 2021 13:30', '81.95'], ['11 Feb 2021 19:30', '88.58'], ['11 Feb 2021 20:00', '88.58'], ['01 Apr 2021 00:00', '92.85'], ['01 Apr 2021 00:30', '91.73']]