CODEWITHSUNDEEP
pythonexcelpandasnumpydatetime
Chris B.
Chris B.

Reputation: 465

Datetime.strftime() not modifying properly?

I'm trying to change the datetime objects in a list-of-lists to strings using strftime, but the conversion to string is acting confusingly. Specifically, I'm trying to format it as %H:%M

I've parsed an Excel file with Pandas and converted the DataFrame into a list-of-lists using NumPy.

Here's the relevant section(s) of my code

import pandas as pd
import datetime
import time

... 

dataframe = pd.read_excel(download_file, skiprows=4)
location_logs = dataframe.to_numpy().tolist()

for log in location_logs:
    for val in log:
        if type(val) == datetime.datetime:
            val = val.strftime("%H:%M")

The loop is identifying datetime objects correctly as a print statement inside the conditional matches the data and even prints the formatted string instead of the datetime object.

However, if I print a list such as location_logs[0], it prints the datetime object found in the nested list instead of the string, i.e., printing datetime.datetime(2019,6,17,23,59) instead of my expected 23:59

Am I going about converting datetime objects incorrectly? Is it possible the size of the list-of-lists is causing an issue? There are ~62k lists with 7 elements in each list.

Upvotes: 0

Views: 488

Answers (1)

René
René

Reputation: 4827

Maybe try something like:

location_logs = [datetime.datetime(2009, 9, 12, 11, 23, 44), datetime.datetime(2019, 7, 10, 6, 21, 15)]

for i in range(len(location_logs)):
    if type(location_logs[i]) == datetime.datetime:
        location_logs[i] = location_logs[i].strftime("%H:%M")

location_logs

Result:

['11:23', '06:21']

Upvotes: 1

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