Get a distribution function from a vector of values after applying some weights
getWeightedDf(y, y.seq = NULL, weights = NULL, norm = TRUE)a vector to compute the mean for
an optional vector of values to compute the distribution function for; the default is to use all unique values of y
the vector of weights, can be NULL, then will just return mean
normalize the weights so that they have mean of 1, default is to normalize
ecdf