find_datetime_variables#

With find_datetime_variables() you can automatically capture in a list the names of all datetime variables in a dataset, whether they are parsed as datetime or object.

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="min")
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.

We can use find_datetime_variables() to capture all datetime variables regardless of their data type. So let’s do that and then display the list:

from feature_engine.variable_handling import find_datetime_variables

var_date = find_datetime_variables(X)

var_date

Below we see the variable names in the list:

['date1', 'date2', 'date3']

Note that find_datetime_variables() captures all 3 datetime variables. The first 2 are of type datetime, whereas the third variable is of type object. But as it can be parsed as datetime, it will be captured in the list as well.

If there are no datetime variables, find_datetime_variables() will raise an error. To return an empty list instead, use the argument return_empty to True.

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