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check_datetime_variables#

check_datetime_variables() checks that the variables in the list are, or can be parsed as datetime.

Let’s create a toy dataset with numerical, categorical and datetime variables:

import pandas as pd
from sklearn.datasets import make_classification

X, y = make_classification(
    n_samples=1000,
    n_features=4,
    n_redundant=1,
    n_clusters_per_class=1,
    weights=[0.50],
    class_sep=2,
    random_state=1,
)

# transform arrays into pandas df and series
colnames = [f"num_var_{i+1}" for i in range(4)]
X = pd.DataFrame(X, columns=colnames)

X["cat_var1"] = ["Hello"] * 1000
X["cat_var2"] = ["Bye"] * 1000

X["date1"] = pd.date_range("2020-02-24", periods=1000, freq="T")
X["date2"] = pd.date_range("2021-09-29", periods=1000, freq="H")
X["date3"] = ["2020-02-24"] * 1000

print(X.head())

We see the resulting dataframe below:

   num_var_1  num_var_2  num_var_3  num_var_4 cat_var1 cat_var2  \
0  -1.558594   1.634123   1.556932   2.869318    Hello      Bye
1   1.499925   1.651008   1.159977   2.510196    Hello      Bye
2   0.277127  -0.263527   0.532159   0.274491    Hello      Bye
3  -1.139190  -1.131193   2.296540   1.189781    Hello      Bye
4  -0.530061  -2.280109   2.469580   0.365617    Hello      Bye

                date1               date2       date3
0 2020-02-24 00:00:00 2021-09-29 00:00:00  2020-02-24
1 2020-02-24 00:01:00 2021-09-29 01:00:00  2020-02-24
2 2020-02-24 00:02:00 2021-09-29 02:00:00  2020-02-24
3 2020-02-24 00:03:00 2021-09-29 03:00:00  2020-02-24
4 2020-02-24 00:04:00 2021-09-29 04:00:00  2020-02-24

The dataframe has 3 datetime variables, two of them are of type datetime and one of type object.

Let’s check that a list of variables can be parsed as datetime:

from feature_engine.variable_handling import check_datetime_variables

var_date = check_datetime_variables(X, ["date2", "date3"])

var_date

In this case, both variables, if they can be parsed as datetime, will be in the resulting list:

['date2', 'date3']

If we pass a variable that can’t be parsed as datetime, check_datetime_variables() will return an error:

check_datetime_variables(X, ["date2", "cat_var1"])

Below the error message:

TypeError: Some of the variables are not or cannot be parsed as datetime.
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