I have a polars dataframe that contains a datetime column. I want to convert this column to strings in the format %Y%m. For example, all dates in January 2024 should be converted to "202401".
from datetime import datetime
import polars as pl
data = {
"ID" : [1,2,3],
"dates" : [datetime(2024,1,2),datetime(2024,1,3),datetime(2024,1,4)],
}
df = pl.DataFrame(data)
I have tried using strftime. However, the following AttributeError is raised.
AttributeError: 'Expr' object has no attribute 'strftime'
you can use strftime like this:
df = df.with_columns(pl.col("dates").dt.strftime("%Y%m"))
print(df)
┌─────┬────────┐
│ ID ┆ dates │
│ --- ┆ --- │
│ i64 ┆ str │
╞═════╪════════╡
│ 1 ┆ 202401 │
│ 2 ┆ 202401 │
│ 3 ┆ 202401 │
└─────┴────────┘
Note that pl.Expr.dt.strftime is available under the pl.Expr.dt namespace. Hence, it is called on the dt attribute of an expression and not the expression directly.
df.with_columns(
pl.col("dates").dt.strftime("%Y%m")
)
shape: (3, 2)
┌─────┬────────┐
│ ID ┆ dates │
│ --- ┆ --- │
│ i64 ┆ str │
╞═════╪════════╡
│ 1 ┆ 202401 │
│ 2 ┆ 202401 │
│ 3 ┆ 202401 │
└─────┴────────┘