For anyone interested in data analysis in R or Python (specifically Wickham&#x27;s dplyr or McKinney&#x27;s pandas), I can&#x27;t recommend reading Wickham&#x27;s paper on the split-apply-combine methodology enough. It really helped me understand working without looping.<p>The paper&#x27;s examples might be slightly dated as they use dplyr&#x27;s predecessor, plyr. I imagine they&#x27;re pretty similar though.<p><a href="http:&#x2F;&#x2F;vita.had.co.nz&#x2F;papers&#x2F;plyr.html" rel="nofollow">http:&#x2F;&#x2F;vita.had.co.nz&#x2F;papers&#x2F;plyr.html</a>