I have a dataset that unequal number of repetition. I want to subset a data by removing those entries that are incomplete (i.e. replication less than maximum). Just small example: set.seed(123) mydt <- data.frame (name= rep ( c("A", "B", "C", "D", "E"), c(1,2,4,4, 3)), var1 = rnorm (14, 3,1), var2 = rnorm (14, 4,1)) mydt name var1 var2 1 A 2.439524 3.444159 2 B 2.769823 5.786913 3 B 4.558708 4.497850 4 C 3.070508 2.033383 5 C 3.129288 4.701356 6 C 4.715065 3.527209 7 C 3.460916 2.932176 8 D 1.734939 3.782025 9 D 2.313147 2.973996 10 D 2.554338 3.271109 11 D 4.224082 3.374961 12 E 3.359814 2.313307 13 E 3.400771 4.837787 14 E 3.110683 4.153373 summary(mydt) name var1 var2 A:1 Min. :1.735 Min. :2.033 B:2 1st Qu.:2.608 1st Qu.:3.048 C:4 Median :3.120 Median :3.486 D:4 Mean :3.203 Mean :3.688 E:3 3rd Qu.:3.446 3rd Qu.:4.412 Max. :4.715 Max. :5.787 I want to get rid of A, B, E from the data as they are incomplete. Thus expected output: name var1 var2 4 C 3.070508 2.033383 5 C 3.129288 4.701356 6 C 4.715065 3.527209 7 C 3.460916 2.932176 8 D 1.734939 3.782025 9 D 2.313147 2.973996 10 D 2.554338 3.271109 11 D 4.224082 3.374961 Please note the dataset is big, the following may not a option: mydt[mydt$name == "C",] mydt[mydt$name == "D", ]