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Combine Data and Time

Source code

Description

Create a naive Datetime from an existing Date/Datetime expression and a Time. Each date/datetime in the first half of the interval is mapped to the start of its bucket. Each date/datetime in the second half of the interval is mapped to the end of its bucket.

Usage

<Expr>$dt$combine(tm, tu = "us")

Arguments

tm Expr or numeric or PTime, the number of epoch since or before(if negative) the Date or tm is an Expr e.g. a column of DataType ‘Time’ or something into an Expr.
tu time unit of epochs, default is "us", if tm is a PTime, then tz passed via PTime.

Details

The tu allows the following time time units the following string language:

  • 1ns \# 1 nanosecond
  • 1us \# 1 microsecond
  • 1ms \# 1 millisecond

Value

Date/Datetime expr

Examples

library(polars)

# Using pl$PTime
pl$lit(as.Date("2021-01-01"))$dt$combine(pl$PTime("02:34:12"))$to_series()

#> polars Series: shape: (1,)
#> Series: '' [datetime[ns]]
#> [
#>  2021-01-01 02:34:12
#> ]

pl$lit(as.Date("2021-01-01"))$dt$combine(pl$PTime(3600 * 1.5, tu = "s"))$to_series()

#> polars Series: shape: (1,)
#> Series: '' [datetime[ns]]
#> [
#>  2021-01-01 01:30:00
#> ]

pl$lit(as.Date("2021-01-01"))$dt$combine(pl$PTime(3600 * 1.5E6 + 123, tu = "us"))$to_series()

#> polars Series: shape: (1,)
#> Series: '' [datetime[ns]]
#> [
#>  2021-01-01 01:30:00.000123
#> ]

# pass double and set tu manually
pl$lit(as.Date("2021-01-01"))$dt$combine(3600 * 1.5E6 + 123, tu = "us")$to_series()

#> polars Series: shape: (1,)
#> Series: '' [datetime[μs]]
#> [
#>  2021-01-01 01:30:00.000123
#> ]

# if needed to convert back to R it is more intuitive to set a specific time zone
expr = pl$lit(as.Date("2021-01-01"))$dt$combine(3600 * 1.5E6 + 123, tu = "us")
expr$cast(pl$Datetime("us", "GMT"))$to_r()

#> [1] "2021-01-01 01:30:00 GMT"