Function assesses whether the inputs correspond to the requirements for scoring quantile-based forecasts.
check_input_quantile(observed, predicted, quantile_level)
Returns TRUE if the check was successful and a string with an error message otherwise.
Input to be checked. Should be a numeric vector with the observed values of size n.
Input to be checked. Should be nxN matrix of predictive
quantiles, n (number of rows) being the number of data points and N
(number of columns) the number of quantiles per forecast.
If observed
is just a single number, then predicted can just be a
vector of size N.
Input to be checked. Should be a vector of size N that denotes the quantile levels corresponding to the columns of the prediction matrix.