DF = data.frame(data=c(8, 12, 97, 103, 19, 21, 25, 27, 29, 30),
                group=c(rep(1, 4), rep(2, 6)))
print(DF)

DF$data_rank = order(DF$data)
print(DF)

## Wilcoxon rank-sum test:
##
group_1_sum = sum(DF$data_rank[DF$group==1])
group_2_sum = sum(DF$data_rank[DF$group==2])
print(c(group_1_sum, group_2_sum))

## Median test:
##
med = median(DF$data)
print(med)
DF$above_median = FALSE
DF$above_median[DF$data > med] = TRUE
print(DF)

T = table(DF$group, DF$above_median)
rownames(T) = c('group_1', 'group_2')
colnames(T) = c('below_median', 'above_median')
print(T)