Convert a String column into a Date/Datetime/Time column.

Source code

Description

Similar to the strptime() function.

Usage

<Expr>$str$strptime(
  dtype,
  format = NULL,
  ...,
  strict = TRUE,
  exact = TRUE,
  cache = TRUE,
  ambiguous = "raise"
)

Arguments

dtype	The data type to convert into. Can be either pl$Date, pl$Datetime(), or pl$Time.
format	Format to use for conversion. Refer to the chrono crate documentation for the full specification. Example: “%Y-%m-%d %H:%M:%S”. If NULL (default), the format is inferred from the data. Notice that time zone %Z is not supported and will just ignore timezones. Numeric time zones like %z or %:z are supported.
…	Not used.
strict	If TRUE (default), raise an error if a single string cannot be parsed. If FALSE, produce a polars null.
exact	If TRUE (default), require an exact format match. If FALSE, allow the format to match anywhere in the target string. Conversion to the Time type is always exact. Note that using exact = FALSE introduces a performance penalty - cleaning your data beforehand will almost certainly be more performant.
cache	Use a cache of unique, converted dates to apply the datetime conversion.
ambiguous	Determine how to deal with ambiguous datetimes: “raise” (default): throw an error “earliest”: use the earliest datetime “latest”: use the latest datetime “null”: return a null value

Details

When parsing a Datetime the column precision will be inferred from the format string, if given, e.g.: “%F %T%.3f” => pl$Datetime("ms"). If no fractional second component is found then the default is “us” (microsecond).

Value

Expr of Date, Datetime or Time type

See Also

• \$str$to_date()
• \$str$to_datetime()
• \$str$to_time()

Examples

library("polars0")

# Dealing with a consistent format
s = as_polars_series(c("2020-01-01 01:00Z", "2020-01-01 02:00Z"))

s$str$strptime(pl$Datetime(), "%Y-%m-%d %H:%M%#z")

#> polars Series: shape: (2,)
#> Series: '' [datetime[μs, UTC]]
#> [
#>  2020-01-01 01:00:00 UTC
#>  2020-01-01 02:00:00 UTC
#> ]

# Auto infer format
s$str$strptime(pl$Datetime())

#> polars Series: shape: (2,)
#> Series: '' [datetime[μs, UTC]]
#> [
#>  2020-01-01 01:00:00 UTC
#>  2020-01-01 02:00:00 UTC
#> ]

# Datetime with timezone is interpreted as UTC timezone
as_polars_series("2020-01-01T01:00:00+09:00")$str$strptime(pl$Datetime())

#> polars Series: shape: (1,)
#> Series: '' [datetime[μs, UTC]]
#> [
#>  2019-12-31 16:00:00 UTC
#> ]

# Dealing with different formats.
s = as_polars_series(
  c(
    "2021-04-22",
    "2022-01-04 00:00:00",
    "01/31/22",
    "Sun Jul  8 00:34:60 2001"
  ),
  "date"
)

s$to_frame()$select(
  pl$coalesce(
    pl$col("date")$str$strptime(pl$Date, "%F", strict = FALSE),
    pl$col("date")$str$strptime(pl$Date, "%F %T", strict = FALSE),
    pl$col("date")$str$strptime(pl$Date, "%D", strict = FALSE),
    pl$col("date")$str$strptime(pl$Date, "%c", strict = FALSE)
  )
)

#> shape: (4, 1)
#> ┌────────────┐
#> │ date       │
#> │ ---        │
#> │ date       │
#> ╞════════════╡
#> │ 2021-04-22 │
#> │ 2022-01-04 │
#> │ 2022-01-31 │
#> │ 2001-07-08 │
#> └────────────┘

# Ignore invalid time
s = as_polars_series(
  c(
    "2023-01-01 11:22:33 -0100",
    "2023-01-01 11:22:33 +0300",
    "invalid time"
  )
)

s$str$strptime(
  pl$Datetime("ns"),
  format = "%Y-%m-%d %H:%M:%S %z",
  strict = FALSE
)

#> polars Series: shape: (3,)
#> Series: '' [datetime[ns, UTC]]
#> [
#>  2023-01-01 12:22:33 UTC
#>  2023-01-01 08:22:33 UTC
#>  null
#> ]