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Dear R experts, I am having difficulty using loops productively and would like to please ask for advice. I have a dataframe of ids and groups. I would like to break down the dataframe into groups, find the unique sets of ids, then reassemble. My thought was to use a loop, but I have been unable to finish this loop in a logical way. I would like to find the unique ids for group 1, group 2,

Hello, I would like to please ask if someone would explain how r reads characters and numbers differently. Using read.csv, I had a matrix that resembled the following, only with many more ids and data: ID Visit variable 2 1 5 2 1 3 2 3 4 2 41 1 2 42 34 2 5 54 2 9 1 2 10 3 2 12 5 5 1 54 5 2 9 5 3 3 5 41 54 5 41 2 5 5 235 5 9 4 5 10 2 5 12

Dear R experts, I would like to please ask for your help with repeating steps in an apply statement. I have a dataframe that lists multiple variables for a given id and visit, as well as drug treatment. > head(exp) id visit variable1 variable2 variable3 variable4 drug 1 3 1 13 10 7 11 0 2 3 5 10 15 9 9 0 3 3 12

Hi, I have a series of id's with multiple visits and questionnaire scores. This is a clinical trial that will be analyzed using the last observation carried forward method. In other words, in order to comply with intent to treat analysis when many subjects withdraw, data points for the last visit must be generated and filled in with the last observation. The ultimate goal is to tabulate the