# Correction controle continu
# fevrier 2019
# algorithme 

A <- as.vector(c(8,5,5,4,3,4,6))
B <- as.vector(c(0,0,0,0,0,0,0))
C <- as.vector(c(0,0,0,0,0,0,0,0))
k <- 8

for (i in 1:length(A)) 
  C[A[i]] <- C[A[i]] +1
print(C)
# 0 0 1 2 2 1 0 1

for (i in 2:k)
  C[i] <- C[i] + C[i-1]
print(C)
# 0 0 1 3 5 6 6 7

for (i in length(A):1)
{
  B[C[A[i]]] <- A[i]
  C[A[i]] <- (C[A[i]] - 1)
}

print(C) # 0 0 0 1 3 5 6 6
print(A) # 8 5 5 4 3 4 6

# tableau trie :
print(B) # 3 4 4 5 5 6 8

a <- matrix(c(1,2,3,4,5,6), ncol = 3, nrow=3)
mean(a[,1])
mean(a[,3])
mean(a[,2:3])
mean(a)

b <- rbind(a, c(10,11,12))
#      [,1] [,2] [,3]
#[1,]    1    3    5
#[2,]    2    4    6
#[3,]   10   11   12

cc <- a%*%b
#     [,1] [,2] [,3]
#[1,]   57   70   83
#[2,]   70   88  106

ilist <- list(El1 = cc[,1], El2 = cc[,2], El3 = cc[,3])
sort(sapply(ilist,mean))
# 63.5 79.0 94.5 

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