Filter a time series of vertical profiles ('vpts') by a start and end time,
for night or day time, or extract profile nearest to provided timestamp.
Use argument night = TRUE to select only time stamps between sunset and sunrise,
or night = FALSE to select daytime (sunrise to sunset). Selection for night and day uses
check_night()
.
Arguments
- x
A
vpts
object.- min
POSIXct date or character. Minimum datetime to be included.
- max
POSIXct date or character. Datetime up to this maximum included.
- nearest
POSIXct date or character. If specified,
min
andmax
are ignored and the profile (vp
) nearest to the specified datetime is returned that matches the day/night selection criteria.- night
When
TRUE
selects only nighttime profiles, whenFALSE
selects only daytime profiles, as classified bycheck_night()
.- elev
Numeric (vector). Sun elevation in degrees defining nighttime. May also be a numeric vector of length two, with first element giving sunset elevation, and second element sunrise elevation.
- offset
Numeric (vector). Time duration in seconds by which to shift the start and end of nighttime. May also be a numeric vector of length two, with first element added to moment of sunset and second element added to moment of sunrise. See
check_night()
for details.
Details
Returns profiles for which min <= timestamp profile < max. Selection for night and day occurs by check_night.
Examples
# Select profiles later than 02 Sep 2016
# Select the profile nearest to 2016-09-01 03:00 UTC
filter_vpts(example_vpts, nearest = "2016-09-01 03:00")
#> Vertical profile (class vp)
#>
#> radar: KBGM
#> source:
#> nominal time: 2016-09-01 03:02:00
#> generated by:
# Select profiles between than 01:00 and 03:00 UTC on 02 Sep 2016
filter_vpts(example_vpts, min = "2016-09-02 01:00", max = "2016-09-02 03:00")
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 13
#> time range (UTC): 2016-09-02 01:04:00 - 2016-09-02 02:59:00
#> time step (s): min: 540 max: 600
# Select daytime profiles (i.e. profiles between sunrise and sunset)
filter_vpts(example_vpts, night = FALSE)
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 910
#> time range (UTC): 2016-09-01 10:35:00 - 2016-09-10 11:56:00
#> time step (s): min: 180 max: 41460
# Select nighttime profiles, with nights starting and ending at
# civil twilight (when the sun is 6 degrees below the horizon)
filter_vpts(example_vpts, night = TRUE, elev = -6)
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 938
#> time range (UTC): 2016-09-01 00:10:00 - 2016-09-10 10:10:00
#> time step (s): min: 180 max: 55200
# Select nighttime profiles from 3h after sunset to 2h before sunrise
filter_vpts(example_vpts, night = TRUE, offset = c(3, -2)*3600)
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 578
#> time range (UTC): 2016-09-01 02:39:00 - 2016-09-10 08:41:00
#> time step (s): min: 180 max: 65460