I apologize if this is a relatively easy problem, but have been stuck on this issue for a few days. I am attempting to combine values from 2 separate dataframes. Each dataframe contains a shared identifier (GROUP). Dataframe 1 (3272 rows x 3 columns) further divides this shared grouping factor into unique identifiers (ID), as well as contains the proportion of the GROUP area of which the unique identifier consists (PROP_AREA). Dataframe 2 (291 x 14976) in addition to consisting of the shared identifier, also has numerous columns consisting of values (VALUE1, VALUE2). I would like to multiply the PROP_AREA in dataframe 1 by each value in dataframe 2 (VALUE1 through VALUE14976) based on the GROUP factor, constructing a final dataframe of size 3272 x 14976. An example of the data frames are as follows:
frame1: ID GROUP PROP_AREA 1 A 0.33 2 A 0.33 3 A 0.33 4 B 0.50 5 B 0.50 6 C 1.00 7 D 1.00 frame2: GROUP VALUE1 VALUE2 A 10 5 B 20 10 C 30 15 D 40 20 Desired dataframe frame3: ID VALUE1 VALUE2 1 3.3 1.65 2 3.3 1.65 3 3.3 1.65 4 10 5 5 10 5 6 30 15 7 40 20 I assume I would need to use the %in% function or if statements, but am unsure how to write the code. I have attempted to construct a for loop with an if statement, but have not been successful as of yet. for(i in 1:nrow(frame1)) { for(j in 2:ncol(frame2)) { if (frame1$GROUP[i] == frame2$GROUP[i]) { frame3[i,j+1] <- frame1$PROP_AREA[i]*frame2[i,j+1] } } } Any advice on suggested code or packages to read up on would be much appreciated. Brock [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.