Aggregates a data frame to monthly resolution
agg2monthly(df, col_name, fun, allow_na = 0)
A data frame with the Date and the aggregated variable(s).
data frame with class Date or POSIXct in the first column.
string (vector) with the name(s) of the column(s) to aggregate.
string (vector) containing the name(s) of function(s) to use: mean, min, max, sum, last or first.
optional. Numeric value with the maximum allowed number of NA_real_ values. By default the function will not tolerate any NA_real_ in an aggregation period (and will return NA_real_ instead).