How to filter data in R?

Question

I have huge data sets which contains more than millions of rows and has some peculiar attributes. I need to filter the data retaining its other properties.

My data i

Answer 1

You may try

library(data.table)
setDT(df1)[, .SD[any(Prop1!=Prop2)], ID]
#          ID Prop1 Prop2 TotalProp
# 1: 56892558   A61   G02         4
# 2: 56892558   A61   A61         4
# 3: 56892558   G02   A61         4
# 4: 56892558   A61   A61         4
# 5: 56892552   B61   B61         3
# 6: 56892552   B61   B61         3
# 7: 56892552   B61   A61         3
# 8: 56892559   B61   G61         3
# 9: 56892559   B61   B61         3
#10: 56892559   B61   B61         3

Or as @Frank suggested

setDT(df1)[, if(any(Prop1!=Prop2)) .SD, ID]

Similar option using dplyr

library(dplyr)
df1 %>%
    group_by(ID) %>%
    filter(any(Prop1!=Prop2))

Or using ave from base R

df1[with(df1, ave(Prop1!=Prop2, ID, FUN=any)),]