Hi, I am trying to add a column of numbers to a data frame in R with multiple conditions.
Here is a simplified example df: [A] [B] [C] [D] [E] [1] 1 X 90 88 [2] 1 Y 72 70 [3] 1 Z 67 41 [4] 2 X 74 49 [5] 2 Y 42 50 [6] 2 Z 81 56 [7] 3 X 92 59 [8] 3 Y 94 80 [9] 3 Z 80 82 I would like column [E] to have a certain value (found either in [C] or [D]) based on conditions in columns [A] *and* [B]. E.g. : if [A] = 1 and [B] = X, then [E] = the entry in [C] for that row (i.e., 90) if [A] = 1 and [B] = Y, then [E] = the entry in [D] for that row (i.e., 70) if [A] = 1 and [B] = Z, then [E] = the entry in [C] for that row (i.e., 67) if [A] = 2 and [B] = X, then [E] = the entry in [C] for that row (i.e., 74) if [A] = 2 and [B] = Y, then [E] = the entry in [D] for that row (i.e., 50) if [A] = 2 and [B] = Z, then [E] = the entry in [C] for that row (i.e., 81) and so on. ATTEMPT TO RESOLVE: The following code allowed me to add values for column [E] when [A] ==1, but I can't figure out how to keep the code going in order to get a value for column [E] based on all of the numbers in column [A] and the secondary condition for [B] ([A] goes from 1:48). df$[E] <- ifelse((df$A == 1) & (df$B == "X"), df$C[df$A == 1], ifelse((df$A == 1) & (df$B == "Y"), df$D[df$A == 1], ifelse((df$A == 1) & (df$B == "Z"), df$C[df$A == 1], NA)))) Thank you for any advice you can give. Libby G libbymg[at]utexas.edu [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.