Hi Michael, It could be due to some extra space.? If you use read.table(..., fill=TRUE), it should read.? Then, there would be missing values.? Using ?dput() will be better.? ?dput(df1) structure(list(x = c(2L, 5L, 4L, 6L, 24L, 7L, 12L, 3L, 5L)), .Names = "x", class = "data.frame", row.names = c("A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9")) Now, try the code by assigning: df1<- structure(list(x..... It wouldn't work with decimals because here: 3:5 #[1] 3 4 5 #it will matching all values that are 3,4, and 5 Trying this on another dataset: df2<- structure(list(x = c(2, 5, 4.4, 6, 24, 7, 12, 3.6, 5)), .Names = "x", class = "data.frame", row.names = c("A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9")) vec2<- unlist(df2) ?names(vec2)<- row.names(df2) vec2 #? A1?? A2?? A3?? A4?? A5?? A6?? A7?? A8?? A9 # 2.0? 5.0? 4.4? 6.0 24.0? 7.0 12.0? 3.6? 5.0 ?names(vec2)[vec2%in% 3:5] #incorrect #[1] "A2" "A9" names(vec2)[vec2%in% seq(3,5,by=0.1)] #[1] "A2" "A3" "A8" "A9" #If I change vec2[3]<- 4.46 ?names(vec2)[vec2%in% seq(3,5,by=0.1)] #[1] "A2" "A8" "A9" ?names(vec2)[round(vec2,1)%in% seq(3,5,by=0.1)] #[1] "A2" "A3" "A8" "A9" names(vec2)[vec2>=3 & vec2<=5] #should be better in such cases #[1] "A2" "A3" "A8" "A9" It is also better to check R FAQ 7.31. A.K. Hi Arun, Perhaps these are dataframes I am working with, and have mistaken them for vectors (I am still very new at this and learning the data structures). I tried to read the text in as you have it here (copied and pasted), but it did not work. Error in read.table(text = " \n\"\",\"x\" \n\"A1\",2 \n\"A2\",5 \n\"A3\",4 \n\"A4\",6 \n\"A5\",24 \n\"A6\",7 \n\"A7\",12 \n\"A8\",3 \n\"A9\",5 \n", ?: ? more columns than column names I retried both: names(vec1)[vec1%in% 3:5] & names(vec1)[!is.na(match(vec1,3:5))] before and after processing my current dataframe to a vector but I get a NULL return. I also get a NULL return if I unlist the dataframe and try to execute: names(vec1)[vec1>=3 & vec1<=5] All 3 do work if I keep the dataframe in its original form, instead of using: ?vec1<-unlist(df1) ?names(vec1)<- row.names(df1) ?I discovered another issue, however. I am working with a couple datasets, one of them has whole numbers the other has percentages in place of visits such as: "A1",0.2 "A2",0.5 ?... the two options: names(vec1)[vec1%in% 3:5] names(vec1)[!is.na(match(vec1,3:5))] do not seem to work with ranges given in decimals (and that is probably what I originally tested them on) but are fine with whole numbers. Thanks, steele