approx (interpolation) for use in a dplyr pipeline.
approx_fun_constant(year, value, rule = 1)Numeric year, in a melted tibble or data frame
Numeric value to interpolate
Rule to use; see approx and details
Interpolated values.
This is a slight change to approx_fun that can be used if there is only one value, not two to interpolate between.
This function will apply the one value you do have to all other years in a grouping.
df <- data.frame(year = 1:5, value = c(1, 2, NA, 4, 5))
approx_fun_constant(df$year, df$value, rule = 2)
#> [1] 1 2 2 4 5