R dplyr: Non-Standard Evaluation difficulty. Would like to use dynamic variable names in filter and mutate

Question

I have created a reproducible example to illustrate the problem I am having with non-standard evaluation in R (dplyr). I would like to use dynamic variable names in the scen

Answer 1

Here is one option with parse_expr from rlang

library(rlang)
library(dplyr)
patientData %>%
        filter(!! parse_expr(paste(firstDateName, ">", secondDateName)))
#   patientID    birth_d    treat_d    death_d
#1         5 2017-01-01 2011-12-27 2012-12-26
#2         7 2011-06-25 2012-06-24 2001-01-01
#3        12 2018-05-05 2013-09-17 2014-09-17

Answer 2

1) rlang Use sym like this:

library(dplyr)
library(rlang)

firstDateName <- sym("birth_d")
secondDateName <- sym("death_d")
badRecords <- patientData %>% filter(!!firstDateName > !!secondDateName)

giving:

> badRecords
  patientID    birth_d    treat_d    death_d
1         5 2017-01-01 2011-12-27 2012-12-26
2         7 2011-06-25 2012-06-24 2001-01-01
3        12 2018-05-05 2013-09-17 2014-09-17

2) Base R or in base R:

firstDateName <- "birth_d"
secondDateName <- "death_d"
is.bad <- patientData[[firstDateName]] > patientData[[secondDateName]]
badRecords <- patientData[is.bad, ]

2a) subset Another base solution would be to replace the last two lines above with:

subset(patientData, get(firstDateName) > get(secondDateName))