Subsetting start-stop format datasets

Returns subsets of a data.table like object in the start-stop format. Contrary to the usual subset function, this function subsets (and truncates) specific time-intervals and does not use a logical expression to subset data based on other column values. May be useful to limit start-stop based datasets to a certain time-range.

Usage

subset_start_stop(data, first_time, last_time,
                  truncate=TRUE, start="start",
                  stop="stop", na.rm=FALSE)

Arguments

data

A data.table like object including at least two columns: start (the beginning of the time-interval) and stop (the end of the time-interval). May also be any object that can be coerced to be a data.table, such as a data.frame or a tibble. Intervals should be coded as [start, stop), like in all other functions of this package.

first_time

A single value or a vector of size nrow(data) of class numeric, Date or something similar, specifying the first time that should be kept in the output. All intervals ending before this value will be removed. Additionally, if truncate=TRUE, all intervals starting before first_time and ending after first_time will be truncated to start at first_time.

last_time

A single value or a vector of size nrow(data) of class numeric, Date or something similar, specifying the last time that should be kept in the output. All intervals beginning before this value will be removed. Additionally, if truncate=TRUE, all intervals starting before last_time and ending after last_time will be truncated to end at last_time.

truncate

Either TRUE or FALSE, controls whether existing intervals should be truncated at first_time and or last_time. See the respective arguments for more info.

start

A single character string specifying a column in data specifying the beginning of a time-interval. Defaults to "start".

stop

A single character string specifying a column in data specifying the ending of a time-interval. Defaults to "stop".

na.rm

Either TRUE or FALSE (default), controls whether to remove rows where either first_time or last_time is NA.

Value

Returns a single data.table containing the subsetted start-stop data.

Author

Robin Denz

See also

merge_start_stop, fill_gaps_start_stop, simplify_start_stop

Examples

library(MatchTime)
library(data.table)

# define some example start-stop data
data <- data.table(id=c(1, 1, 1, 1, 1, 2, 2, 2),
                   start=c(0, 10, 25, 812, 1092, 90, 9023, 10000),
                   stop=c(10, 25, 812, 1092, 34334, 8021, 9823, 220022),
                   some_col=c(1, 2, 3, 4, 5, 6, 7, 8))

# limit it to the time-range 28 - 1900
out <- subset_start_stop(data, first_time=28, last_time=1900)
print(out)
#>       id start  stop some_col
#>    <num> <num> <num>    <num>
#> 1:     1    28   812        3
#> 2:     1   812  1092        4
#> 3:     1  1092  1900        5
#> 4:     2    90  1900        6

# don't truncate intervals
out <- subset_start_stop(data, first_time=28, last_time=1900,
                         truncate=FALSE)
print(out)
#>       id start  stop some_col
#>    <num> <num> <num>    <num>
#> 1:     1    25   812        3
#> 2:     1   812  1092        4
#> 3:     1  1092 34334        5
#> 4:     2    90  8021        6

# only cut-off intervals before t = 28
out <- subset_start_stop(data, first_time=28)
print(out)
#>       id start   stop some_col
#>    <num> <num>  <num>    <num>
#> 1:     1    28    812        3
#> 2:     1   812   1092        4
#> 3:     1  1092  34334        5
#> 4:     2    90   8021        6
#> 5:     2  9023   9823        7
#> 6:     2 10000 220022        8

# only cut-off intervals after t = 28
out <- subset_start_stop(data, last_time=28)
print(out)
#>       id start  stop some_col
#>    <num> <num> <num>    <num>
#> 1:     1     0    10        1
#> 2:     1    10    25        2
#> 3:     1    25    28        3

# using different cut-off values for each person
# note that we have to repeat the respective cut-off values as many times
# as each id appears to make this work
out <- subset_start_stop(data, last_time=c(rep(723, 5), rep(815, 3)))
print(out)
#>       id start  stop some_col
#>    <num> <num> <num>    <num>
#> 1:     1     0    10        1
#> 2:     1    10    25        2
#> 3:     1    25   723        3
#> 4:     2    90   815        6