Create intervention objects from Rx input

Source: R/class_rx.R

See details below for Rx specification. Actual parsing is done by parse_rx; this function can be used to debug Rx inputs.

ev_rx(x, y, ...)

# S4 method for mrgmod,character
ev_rx(x, y, ...)

# S4 method for character,missing
ev_rx(x, df = FALSE, ...)

parse_rx(x)

Arguments

x

a model object or character Rx input
y

character Rx input; see details
...

not used at this time
df

if TRUE then a data frame is returned

Value

The method dispatched on model object (mrgmod) returns another model object. The character method returns an event object. The parse_rx function return a list named with arguments for the event object constructor ev.

Rx specification

  • The dose is found at the start of the string by sequential digits; this may be integer, decimal, or in scientific notation

  • Use in to identify the dosing compartment number; must be integer

  • Use q to identify the dosing interval; must be integer or decimal number (but not scientific notation)

  • Use over to indicate an infusion and its duration; integer or decimal number

  • Use x to indicate total number of doses; must be integer

  • Use then or , to separate dosing periods

  • User after to insert a lag in the start of a period; integer or decimal number (but not scientific notation)

Examples

# example("ev_rx")

ev_rx("100")

#> Events:
#>   time amt cmt evid
#> 1    0 100   1    1

ev_rx("100 in 2")

#> Events:
#>   time amt cmt evid
#> 1    0 100   2    1

ev_rx("100 q12 x 3")

#> Events:
#>   time amt ii addl cmt evid
#> 1    0 100 12    2   1    1

ev_rx("100 over 2")

#> Events:
#>   time amt rate cmt evid
#> 1    0 100   50   1    1

ev_rx("100 q 24 x 3 then 50 q12 x 2")

#> Events:
#>   time amt ii addl cmt evid
#> 1    0 100 24    2   1    1
#> 2   72  50 12    1   1    1

ev_rx("100 then 50 q 24 after 12")

#> Events:
#>   time amt ii addl cmt evid
#> 1    0 100  0    0   1    1
#> 2   12  50 24    0   1    1

ev_rx("100.2E-2 q4")

#> Events:
#>   time   amt ii cmt evid
#> 1    0 1.002  4   1    1

ev_rx("100 over 2.23")

#> Events:
#>   time amt     rate cmt evid
#> 1    0 100 44.84305   1    1

ev_rx("100 q 12 x 3")

#> Events:
#>   time amt ii addl cmt evid
#> 1    0 100 12    2   1    1

parse_rx("100 mg q 24 then 200 mg q12")

#> [[1]]
#> [[1]]$time
#> [1] 0
#> 
#> [[1]]$cmt
#> [1] 1
#> 
#> [[1]]$amt
#> [1] 100
#> 
#> [[1]]$ii
#> [1] 24
#> 
#> 
#> [[2]]
#> [[2]]$time
#> [1] 0
#> 
#> [[2]]$cmt
#> [1] 1
#> 
#> [[2]]$amt
#> [1] 200
#> 
#> [[2]]$ii
#> [1] 12
#> 
#>