A biologist measured animals from several species. Across all animals together, two measurements seem to fall together. She suspects mixing the species is hiding the real pattern, just like the penguin bills.
Task: write group_correlations(groups, xs, ys). Row i is one animal: groups[i] is its species, xs[i] and ys[i] are its two measurements.
Return a dictionary with:
"all": the correlation between xs and ys over every animalxs and ys for that species onlyRound every correlation to 2 decimal places.
Every species has at least 3 animals, and inside each species neither measurement is the same for every animal. No species is called "all".