(This article was first published on The Data Monkey, and kindly contributed to R-bloggers)
Here's a quick table of what I think are the most useful apply-style commands in R: | Function | Input | Output | Best for |
| apply | Rectangular | Rectangular or vector | Applying function to rows or columns |
| lapply | Anything | List | Non-trivial operations on almost any data type |
| sapply | Anything | Simplified (if possible) or list | Same as lapply, but with simplified output |
| plyr::ddply | data.frame | data.frame | Applying function to groupings defined by variables |
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