The package currently provides a shave function to convert the upper or lower triangles to NA values and a stretch function with a na.rm argument that lets you remove missing values.

But what if one of the correlation pairs is undefined in the lower triangle? A user might want to keep this entry for completeness but stretch(..., na.rm = TRUE) would remove it. For example:

df <- data.frame(x = 1:10, y = 10:1, z = NA)
df %>% correlate() %>% shave()