R 按行从矩阵中采样

我有以下矩阵:

 Mat1 <- structure(c("Procedure_B", "Procedure_C", "Procedure_B", NA, 
"Procedure_B", "Procedure_A", "Procedure_C", "Procedure_B", NA, 
"Procedure_B", NA, "Procedure_B", NA, NA, "Procedure_A", "Procedure_A", 
"Procedure_C", "Procedure_A", "Procedure_A", "Procedure_B", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_B", "Procedure_A", "Procedure_A", 
NA, NA, "Procedure_C", NA, "Procedure_C", NA, "Procedure_A", 
"Procedure_B", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_B", 
"Procedure_A", "Procedure_B", "Procedure_C", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_C", "Procedure_C", "Procedure_A", NA, 
NA, NA, NA, NA, NA, "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", "Procedure_A", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", "Procedure_B", 
"Procedure_B", "Procedure_B", "Procedure_B", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", "Procedure_C", 
"Procedure_C", NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, NA, NA, NA), dim = c(53L, 5L))

我想从每一行中抽取一个值，其概率如下:

P = c(0.99, 0.002992, 0.003186, 0.003018, 0.000804)

即，对于每一行，其5个值中的每一个具有这些概率

预期输出为53个值.

我试过:

sample(Mat1, size = nrow(Mat1), prob = rep(P, nrow(Mat1)), replace = T)

然而，结果并不符合预期的分布. 我不想在循环/应用中这样做，因为我的矩阵可以有很多行.

这个命令有什么问题？