On 1/10/19 7:00 AM, Paul Miller via R-help wrote:
Hello All,
Would like to keep a running total of what drugs cancer patients have taken and
what drugs have been dropped. Searched the Internet and found a way to
cumulatively paste a series of drug names. Am having trouble figuring out how
to make the paste conditional though.
Below is some sample data and code. I'd like to get the paste in the "taken" column to
add a drug only when change = 1. I'd also like to get the paste in the "dropped" column
to add a drug only when change = -1.
You apparently expect us to have pkg:dplyr loaded. The appropriate code
for that would be `library(dplyr)` at the initiation of the example.
Unlike StackOverflow there is no universal expectation in Rhelp of that
preparation.
The `Reduce` function could probably be used if you were willing to
rework two columns into a list that had a sequence of 2 two-element
lists but it's not the first choice for handling this data situation.
Instead consider using `mapply` or perhaps `by`. You are also going to
need to wrap this approach in a programming structure that allows a
patient-focused result to be computed, either `lapply( split( ... ` or
its equivalent in the hadleyverse: `%>% group_by(...`
In the hadleyverse context, you should probably learn to use the purrr
function `map2` for the two-column conditional processing.
--
David.
Thanks,
Paul
sample_data <-
structure(
list(
PTNO = c(82320L, 82320L, 82320L),
change = c(1, 1, -1),
drug = c("cetuximab", "docetaxel", "cetuximab")),
class = c("tbl_df", "tbl", "data.frame"),
row.names = c(NA, -3L)
) %>%
mutate(
taken = Reduce(function(x1, x2) paste(x1, x2, sep = ", "), drug,
accumulate = TRUE),
dropped = Reduce(function(x1, x2) paste(x1, x2, sep = ", "), drug,
accumulate = TRUE)
)
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