al-ilm-nn-pyr-keras-3.r

items <- list(x_train, y_train, x_test, y_test)

dim_formatter <- function (x) {
    if (length(dim(x)) > 2)
        paste("(", dim(x)[1], ", ", dim(x)[2], " , ", dim(x)[3], " , ", dim(x)[4], ")", sep = "")
    else
        paste("(", dim(x)[1], ", ", dim(x)[2], ")", sep = "")
}

# training set
unlist(lapply(items[1:2], function(x) class(x)))    # [1] "array"  "matrix"
unlist(lapply(items[1:2], dim_formatter))           # [1] "(50000, 32 , 32 , 3)" "(50000, 1)"

# testing set
unlist(lapply(items[3:4], function(x) class(x)))    # [1] "array"  "matrix"
unlist(lapply(items[3:4], dim_formatter))           # [1] "(10000, 32 , 32 , 3)" "(10000, 1)"