time_point_cast: Cast a time point between precisions

In clock: Date-Time Types and Tools

Cast a time point between precisions

Description

Casting is one way to change a time point's precision.

Casting to a less precise precision will completely drop information that is more precise than the precision that you are casting to. It does so in a way that makes it round towards zero. When converting time points to a less precise precision, you often want time_point_floor() instead of time_point_cast(), as that handles pre-1970 dates (which are stored as negative durations) in a more intuitive manner.

Casting to a more precise precision is done through a multiplication by a conversion factor between the current precision and the new precision.

Usage

time_point_cast(x, precision)

Arguments

x	⁠[clock_sys_time / clock_naive_time]⁠ A sys-time or naive-time.
precision	⁠[character(1)]⁠ A time point precision. One of: "day" "hour" "minute" "second" "millisecond" "microsecond" "nanosecond"

Value

x cast to the new precision.

Examples

# Hour precision time points
# One is pre-1970, one is post-1970
x <- duration_hours(c(25, -25))
x <- as_naive_time(x)
x

# Casting rounds the underlying duration towards 0
cast <- time_point_cast(x, "day")
cast

# Flooring rounds the underlying duration towards negative infinity,
# which is often more intuitive for time points.
# Note that the cast ends up rounding the pre-1970 date up to the next
# day, while the post-1970 date is rounded down.
floor <- time_point_floor(x, "day")
floor

# Casting to a more precise precision, hour->millisecond
time_point_cast(x, "millisecond")

clock documentation built on Sept. 11, 2024, 8:39 p.m.