I am trying to apply a simple function in a rolling manner to a vector in R using the rollapply function from the zoo package. However, I am encountering an unexpected behavior where the result has multiple columns instead of the expected single column.
Here is my code:
library(zoo)
set.seed(101)
foo <- data.frame("V1" = sample(seq(-5, 5), replace = TRUE, size = 100))
result <- rollapply(foo$V1,
width = 5,
FUN = function(x) ifelse(x < 0, "Yes", "No"),
align = "right",
by.column = FALSE,
fill = NA)
head(result)
I expected result to be a single column vector containing the "Yes" and "No" values for each rolling window of 5 elements in the "V1" column. However, the output I get is a matrix with 6 rows and 5 columns instead.
Can someone please help me understand why I am getting multiple columns in the result and how I can modify the code to obtain a single column result as intended?
Thank you in advance for your assistance!
Dirty way to solve the issue:
# Loop through the elements in foo$V1 using a rolling window of 5
for (i in 1:(length(foo$V1) - 4)) {
# Check if there is a negative number in the current 5-element window
foo$V2[i + 4] <- any(foo$V1[i:(i + 4)] < 0)
}
