Remove rows with the same value across all columns

Question

Suppose I have a data frame (df) that looks like below:

options(stringsAsFactors = F)

cars <- c(\"Car1\", \"Car2\", \"Car3\", \"Car4\", \"Car5\", \"Car6\         


        

Answer 1

keep <- apply(df[2:8], 1, function(x) length(unique(x[!is.na(x)])) != 1)
df[keep, ]

  cars test1 test2 test3 test4 test5 test6 test7
1 Car1     0     0     1     2     0     1     3
3 Car3     3     2     5     2     1     1     2
5 Car5     4     0     2     2     0     1     0
7 Car7     1     2     6     1     1     3     1
8 Car8     3     5     7     1     3     4     1