Working with very small values in R

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When you’re working on extremely small floating numbers in R (such as when you have strong p-values), there are a few options.

  1. Rmpfr package
  2. Parse the string of values in scientific notation. Let’s say you have small values in P column in a dataframe df and those numbers are represented as 1e-400 etc. Then, you can run something like this to parse and compute the log10(P) value.
df %>%
separate(P, c('P_base', 'P_exp'), sep='e', remove=F, fill='right') %>%
replace_na(list(P_exp='0')) %>%
mutate(log10P = log10(as.numeric(P_base)) + as.numeric(P_exp))