I have a drug-trial study dataset (attached image).
Since its a large and complex dataset (at least to me) and I hope to be as
clear as possible with my question.
The dataset is from a study where individuals are given drugs and followed up
over a period spanning two consecutive years. Individuals do not start
treatment on the same day and once they start, the variable "drug-admin" is
marked "x" as well as the time they stop treatment in the following year.
There exists another variable, "study_id", that I hope to populate as can be
seen in the dataset, with the following conditions:
For every individual
• if the individual has entries that show they received drugs both on the
start and end date (marked with the "x")
• if the start of drug administration falls in month == 2 | 3 and end of
administration falls in month == 2 | 4
• then, using the date that marks the start of drug administration, populate
the variable _"study_id"_ in all the rows that fall within the timeframe that
the individual was given drugs but excluding the end of drug administration.
I have tried my level best and while I have explored several examples online, I
haven't managed to solve this. The dataset contains close to 6000 individuals
spanning 10 years and my best bet was to use a loop which keeps crushing R
after running for close to 30min. I have also read that dplyr may do the job
but my attempts have been in vain.
sample code
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
individual <- unique (df$ID) #vector of individuals
datalength <- dim(df)[1] #number of rows in dataframe
for (i in 1:length(individual)) {
for (j in 1:datalength) {
start_admin <- df[(df$year == 2007] & df$drug_admin == "x" & c(df$month ==
2 | df$month == 3),1] #capture date of start
end_admin <- df[(df$year == 2008] & df$drug_admin == "x" & c(df$month == 2
| df$month == 4),1] #capture date of end
if(df[datalength,1] == individual(i) & df[datalength,2] >= start_admin &
df[datalength,2] < end_admin) {
df[datalength,6] <- start_admin #populate respective row if condition is
met
}
}
}
-------------------------------------------------------------------------------------------------------------------------------------------------------------------
Above is the code that keeps failing..
Any help is highly appreciated....
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