unroll - w3toppers.com

Unlist a data frame by rows, not columns

We can take the transpose (t) of the dataset and then use c to get a vector output c(t(df1)) #[1] 0 0 0 1 1 0 1 0 1 1 2 1 1 0 3 By doing transpose, we convert the ‘data.frame’ to ‘matrix’. In both data.frame or matrix, unlist/c operations happen columnwise. So, transposing … Read more

Tell gcc to specifically unroll a loop

GCC gives you a few different ways of handling this: Use #pragma directives, like #pragma GCC optimize (“string”…), as seen in the GCC docs. Note that the pragma makes the optimizations global for the remaining functions. If you used #pragma push_options and pop_options macros cleverly, you could probably define this around just one function like … Read more