if(!require(coin)){install.packages("coin")}

set.seed(169)

n = 16

N = n + n

A = runif(n,1,10)
B = A + 5 + rnorm(n,0,4)

Group = factor(c(rep("A", length(A)), rep("B", length(B))))
Y = c(A,B)

boxplot(Y ~ Group)

library(coin)

MW = wilcox_test(Y ~ Group)
MW

Z = MW@statistic@teststatistic
names(Z) = "Z"

Z

   ###         Z
   ### -4.258848

MWa = wilcox.test(Y ~ Group)

MWa

Za = qnorm(MWa$p.value)

Za

   ### [1] -4.584451

r = abs(Z)/sqrt(N)
names(r) = "r"

r

   ###        r
   ### 0.752865

ra = abs(Za)/sqrt(N)
names(ra) = "ra"

ra

   ###        ra
   ### 0.8104241