Converting strings in an array to dates

Question

I have read an array of strings from a TXT file and saved it as an array (of over thousand values) using such a line:

dates = np.genfromtxt('filename.txt', delimiter=";", usecols=(0), dtype=None)

Next, I would like to convert strings into dates. I tried to use the line:

dates2 = dt.datetime.strptime([dates], '"%Y-%m-%d"').date()

however, I got an error:

TypeError: must be string, not list

I figured out that such a code works fine:

data1='"2010-02-28"'
data1_1 = dt.datetime.strptime(data1, '"%Y-%m-%d"').date()

How should I deal with the described problem?

starball · Accepted Answer · 2025-08-24 06:13:52Z

35

dates is a list of strings. So if you want to create a list of dates from its elements:

dates_list = [dt.datetime.strptime(date, '"%Y-%m-%d"').date() for date in dates]

This line iterates over the strings in the dates list and using list comprehension to create a new list of dates.

Note: '"%Y-%m-%d"' is not a mistake. OP's dates are surrounded by quotes.

edited Aug 24 at 6:13

starball♦

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answered May 27, 2015 at 16:16

DeepSpace

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6 Comments

Michael Szczepaniak Over a year ago

I'm using Python 3.7.3 and I needed to remove the double quotes in order for this to work for me.

DeepSpace Over a year ago

@MichaelSzczepaniak that's because your date strings are not surrounded with double-quotes like OP's.

Anuj Gupta Over a year ago

@DeepSpace OP stands for ? to make this work I had to remove double-quotes "

DeepSpace Over a year ago

@AnujGupta Original Poster, ie the quesion asker

DeepSpace Over a year ago

@Confounded the datetime module, which is canonically imported as import datetime as dt

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Nimantha · Accepted Answer · 2021-11-15 16:41:08Z

1

You can use split for faster result:

from datetime import datetime
today = datetime.now().strftime("%Y-%m-%d").split('-')

edited Nov 15, 2021 at 16:41

Nimantha

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answered Feb 16, 2020 at 15:03

PouriaDiesel

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