Create lag and difference variables for a grouped time series (grouped by a variable called "country")

create_lags_diffs.R

# Create lag and difference variables for a grouped time series (grouped by a variable called "country")
#
# @param df a data frame containing the variable to lag and lead
# @param x a column name in `df` to lag and lead
# @param lag integer period to lag and difference
#
# @importFrom tsibble difference
# @importFrom dplyr %>% lag

create_lags_diffs <- function(df, x, lag = 1) {
    x_var <- enquo(x)
    new_var_diff <- str_c(x_var, "_", "diff_", lag)[[2]]
    new_var_lag <- str_c(x_var, "_", "lag_", lag)[[2]]
    tmp <- df %>% group_by(country) %>%
        mutate(!! new_var_diff := tsibble::difference(!! x_var, lag = lag)) %>%
        mutate(!! new_var_lag := dplyr::lag(!! x_var, n = lag))
}