# Define troublesome x and y
x <- c(NA, NA, NA)
y <- c( 1, NA, NA, NA)
both_na <- function(x, y) {
# Add stopifnot() to check length of x and y
stopifnot(length(x)==length(y))
sum(is.na(x) & is.na(y))
}
# Call both_na() on x and y
both_na(x, y)
col_classes <- function(df) {
class_list <- map(df, class)
# Add a check that no element of class_list has length > 1
if (any(map_dbl(class_list, length) > 1)) {
stop("Some columns have more than one class", call. = FALSE)
}
# Use flatten_chr() to return a character vector
flatten_chr(class_list)
}
big_x <- function(df, threshold) {
# Write a check for x not being in df
if(!"x" %in% names(df)){
stop("df must contain variable called x",call.=F)
}
else if("threshold" %in% names(df)){
stop("df must not contain variable called threshold",call.=F)
}
dplyr::filter(df, x > threshold)
}
