What is Vaex function to parse string to datetime64, which equivalent to pandas to_datetime, that allow custom format?

Question

I have date as string (example: 3/24/2020) that I would like to convert to datetime64[ns] format

df2['date'] = pd.to_datetime(df1["str_date"], format='%m/%d/%Y')

Use pandas to_datetime on vaex dataframe will result an error:

ValueError: time data 'str_date' does not match format '%m/%d/%Y' (match)

I have see maybe duplicate question.

df2['pdate']=df2.date.astype('datetime64[ns]')

However, the answer is type casting. My case required to a format ('%m/%d/%Y') parse string to datetime64[ns], not just type cast.

Solution: make custom function, then .apply

Answer 1

vaex can use apply function for object operations, so you can use datetime and np.datetime64 convert each date string, then apply it.

import numpy as np
from datetime import datetime

def convert_to_datetime(date_string):
    return np.datetime64(datetime.strptime(str(date_string), "%Y%m%d%H%M%S"))

df['date']  = df.date.apply(convert_to_datetime)