Time_aggregate {ARPALData}

Aggregate any ARPALdf object (with higher temporal frequency) to hourly, daily, weekly, monthly and yearly temporal frequencies.

Description

Starting from an ARPALdf object with high frequency (e.g., 10mins or hourly), 'Time_aggregate' aggregates the dataset to lower temporal frequencies (e.g., hourly, daily, weekly, monthly and yearly) by station. The output is an ARPALdf object with observations having hourly, daily, weekly, monthly or yearly frequency. The function can be applied only to ARPALdf objects. User can indicate specific variables to aggregate and an aggregation function among mean, median, sum (cumulated), min, max, quantiles, and variability metrics for each variable. It is possible to specify different aggregation functions on the same variable by repeating the name of the variable in 'Var_vec' and specifying the functions in 'Fns_vec'.

Usage

Time_aggregate(Dataset, Frequency, Var_vec = NULL, Fns_vec = NULL, verbose = T)

Arguments

Dataset

ARPALdf dataframe to aggregate.

Frequency

Temporal aggregation frequency. It can be "hourly", "daily", "weekly", "monthly" or "yearly.

Var_vec

Vector of variables to aggregate. If NULL (default) all the variables are averaged, expect for 'Temperature' and 'Snow_height' which are summed.

Fns_vec

Vector of aggregation functions to apply to the selected variables. Available functions are 'mean', 'median', 'min', 'max', 'sum', 'qPP' (PP-th percentile), 'sd', 'var', 'vc' (variability coefficient), 'skew' (skewness) and 'kurt' (kurtosis). Attention: for Wind Speed and Wind Speed Gust only mean, min and max are available; for Wind Direction and Wind Direction Gust only mean is available.

verbose

Logic value (TRUE or FALSE). Toggle warnings and messages. If 'verbose=T' (default) the function prints on the screen some messages describing the progress of the tasks. If 'verbose=F' any message about the progression is suppressed.

Value

A data frame

Examples

## Download hourly observed concentrations during 2020 for station 501 (Milano - Via Marche).
if (require("RSocrata")) {
    data <- get_ARPA_Lombardia_AQ_data(ID_station=501, Date_begin = "2020-01-01",
                                       Date_end = "2020-12-31", Frequency="hourly")
}
## Aggregate all the data to daily frequency
Time_aggregate(Dataset=data,Frequency="daily",Var_vec=NULL,Fns_vec=NULL)
## Aggregate NO2 to weekly maximum concentrations and NOx to weekly minimum concentrations.
Time_aggregate(Dataset=data,Frequency="weekly",Var_vec=c("NO2","NOx"),Fns_vec=c("max","min"))