R/filter_vpts.R
filter_vpts.Rd
Time and night/day selection in a time series of vertical profiles ('vpts')
filter_vpts(x, min, max, nearest, night, elev = -0.268, offset = 0)
A vpts
object.
Minimum datetime to be included. POSIXct value or character string convertible to POSIXct.
Maximum datetime to be included. POSIXct value or character string convertible to POSIXct.
If specified, min
and max
are ignored and the profile nearest to the
specified datetime is returned that matches the day/night selection criteria.
POSIXct value or character string convertible to POSIXct.
When TRUE select only night time profiles, when FALSE select only day time profiles, as classified by check_night.
numeric. Sun elevation in degrees defining night time. May also be a numeric vector of length two, with first element giving sunset elevation, and second element sunrise elevation.
numeric. Time duration in seconds by which to shift the start and end of night time. 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.
Returns profiles for which min <= timestamp profile < max. Selection for night and day occurs by check_night.
# load example vertical profile time series:
data(example_vpts)
example_vpts
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 1934
#> time range (UTC): 2016-09-01 00:02:00 - 2016-09-10 11:56:00
#> time step (s): min: 180 max: 16320
# select profiles later than 02-Sep-2016
filter_vpts(example_vpts, min = "2016-09-02")
#> Irregular time series of vertical profiles (class vpts)
#>
#> radar: KBGM
#> # profiles: 1651
#> time range (UTC): 2016-09-02 00:06:00 - 2016-09-10 11:56:00
#> time step (s): min: 180 max: 16320
# 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 1 and 3 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 day time profiles (day time periods from sunrise to 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 night time profiles, with nights starting 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 night time profiles from 3 hours after sunset to 2 hours 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