A helper function for ordering window function output
This function makes it possible to control the ordering of window functions in R that don't have a specific ordering parameter. When translated to SQL it will modify the order clause of the OVER function.
order_by(order_by, call)
order_by |
a vector to order_by |
call |
a function call to a window function, where the first argument is the vector being operated on |
This function works by changing the call to instead call
with_order() with the appropriate arguments.
order_by(10:1, cumsum(1:10)) x <- 10:1 y <- 1:10 order_by(x, cumsum(y)) df <- data.frame(year = 2000:2005, value = (0:5) ^ 2) scrambled <- df[sample(nrow(df)), ] wrong <- mutate(scrambled, running = cumsum(value)) arrange(wrong, year) right <- mutate(scrambled, running = order_by(year, cumsum(value))) arrange(right, year)
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