Hi, Try this: set.seed(24) df<- data.frame(x=sample(seq(0.25,4.25,by=.05),1e5,replace=TRUE),y= sample(seq(0.10,1.05,by=.05),1e5,replace=TRUE),z=rnorm(1e5))
#Used a shorter vector x1<- c(1.05,2.85,3.40,4.25,0.25) y1<- c(0.25,0.10,0.90,0.25,1.05) res<-do.call(rbind,lapply(seq_along(x1),function(i) subset(df,x==x1[i]&y==y1[i]))) head(res,2) # x y z #466 1.05 0.25 0.7865224 #4119 1.05 0.25 -1.5679096 tail(res,2) # x y z #98120 0.25 1.05 -2.1239596 #98178 0.25 1.05 0.3321464 A.K. Hi Everyone, First time poster so any posting rules i should know about feel free to advise... I've got a data frame of 250 000 rows in columns of x y and z. i need to extract 20-30 rows from the data frame with specific x and y values, such that i can find the z value that corresponds. There is no repeated data. (its actually 250 000 squares in a 5x5m grid) to find them individually i can use subset successfully result<-subset(df,x==1.05 & y==c0.25) gives me the row in the dataframe with that x and y value. so if i have x = 1.05 2.85 3.40 4.25 0.25 3.05 3.70 0.20 0.30 0.70 1.05 1.20 1.40 1.90 2.70 3.25 3.55 4.60 2.05 2.15 3.70 4.85 4.90 1.60 2.45 3.20 3.90 4.45 and y= 0.25 0.10 0.90 0.25 1.05 1.70 2.05 2.90 2.35 2.60 2.55 2.15 2.75 2.05 2.70 2.25 2.55 2.05 3.65 3.05 3.00 3.50 3.75 4.85 4.50 4.50 3.35 4.90 then how can i retrieve the rows for all those values at once. if i name x=xt and y=yt and then result<-subset(df,x==xt & y==yt) then i get result [1] x y Height <0 rows> (or 0-length row.names) i dont understand why zero rows are selected. obviously im applying the vectors inappropriately, but i cant seem to find anything on this method of subsetting online. Thanks for any replies! ______________________________________________ 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.
