[R] R - Populate Another Variable Based on Multiple Conditions | For a Large Dataset

Jeff Newmiller jdnewmil at dcn.davis.ca.us
Sun Jul 3 07:42:52 CEST 2016


You are making this hard on yourself by not paying attention the Posting Guide listed in the footer of every email on this list. You would probably also find [1] helpful also. 

[1] http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
-- 
Sent from my phone. Please excuse my brevity.

On July 2, 2016 3:41:07 PM PDT, Kevin Wamae <KWamae at kemri-wellcome.org> wrote:
>Hi Jeff, sorry for referring to you as Jennifer earlier, accept my
>apologies.
>
>I attached a sample dataset in the question, am afraid it must have
>failed to attach.
>
>I have attached it again..
>
>
>Regards
>-------------------------------------------------------------------------------
>Kevin Kariuki
> 
>
>On 7/2/16, 7:37 PM, "Jeff Newmiller" <jdnewmil at dcn.davis.ca.us> wrote:
>
>I can understand you not wanting to supply your actual data online, but
>only you know what your data looks like so only you can create a
>simulated data set that we could show you how to work with. 
>-- 
>Sent from my phone. Please excuse my brevity.
>
>On July 2, 2016 2:57:39 AM PDT, Kevin Wamae <KWamae at kemri-wellcome.org>
>wrote:
>>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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