check_rows <- function (x) {
if(nrow(x) == 0) stop("x must contain at least one row of data")
TRUE
}
check_columns <- function (x, colnames) {
stopifnot(is.data.frame(x))
stopifnot(is.character(colnames))
colnames <- unique(colnames)
bol <- colnames %in% colnames(x)
if(!all(bol))
stop("x must contain ", plural("column", sum(!bol) > 1, " "), punctuate_strings(colnames[!bol], "and"))
TRUE
}
check_class_columns <- function (x, columns) {
check_columns(x, names(columns))
for(colname in names(columns)) {
if(!class(x[[colname]]) %in% columns[[colname]])
stop("column ", colname, " must be class ", punctuate_strings(columns[[colname]], "or"))
}
TRUE
}
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