How to run multiple t.test in a data.frame?

Question

I have a data,

temp_data <- as.data.frame(matrix(rbinom(9*9, 1, 0.5), ncol=9, nrow =9))
colnames(temp_data) <- paste(rep(c(\"a\",\"b\",\"c\"), each=3), re         


        

Answer 1

You could do this:

pa <- unlist(lapply(1:3, function(i) t.test(temp_data[, i], temp_data[, i + 6])$p.value))
pb <- unlist(lapply(1:3, function(i) t.test(temp_data[, i + 3], temp_data[, i + 6])$p.value))
p <- c(pa, pb)
p.table <- as.matrix(data.frame(factor.1 = colnames(temp_data[1:6]),
           factor.2 = rep(colnames(temp_data[7:9]), 2),
           p.value = p))
p.table
#      factor.1 factor.2 p.value      
# [1,] "a1"     "c1"     "0.652543514"
# [2,] "a2"     "c2"     "0.176463197"
# [3,] "a3"     "c3"     "0.176463197"
# [4,] "b1"     "c1"     "0.372458894"
# [5,] "b2"     "c2"     "0.003949773"
# [6,] "b3"     "c3"     "0.652543514"