Parsing lag functions from strings

Lag-function-range-dynamic-create.R

# See: https://gist.github.com/drsimonj/2038ff9f9c67063f384f10fac95de566
# See: https://adv-r.hadley.nz/meta-big-picture.html
# See: https://dplyr.tidyverse.org/reference/tidyeval.html
# See: https://dplyr.tidyverse.org/articles/programming.html


library(dplyr)

# Set up lags
lags <- c(1:30)

# Name the columns that will contain the lags, with appropriate index
lag_names_RealPower <- glue('lag_{str_pad(lags, nchar(max(lags)), pad = "0")}_RealPower')

# Create list of lag functions, as eval-ed/parse-d labmda functions
lag_functions_RealPower <-
    map(lags, ~ eval(parse(text=glue("~ dplyr::lag(.x, {.x})")))) %>%
    set_names(lag_names_RealPower)

# Compute the lag
tibble(RealPower=1:99) %>%
    mutate_at(vars(RealPower), .funs=lag_functions_RealPower)