This is an excellent resource to understand 2 types of data frame format: Long and Wide.
- Just take a look at figure 1 inside the article
Long format: ggplot2 needs in certain scenarios this kind of format to work (generally grouped plots).
Wide format: On the other hand, usually when you read transnational data, you may find "long-format" and you need it in "wide" in order to create a predictive model.
Here, each row represents a case study, and each column an attribute/variable. Classical input for building a cluster or predictive model.
The most used library to achieve this is "reshape2", and, what's the difference with "reshape"?
Package author said:
"Reshape2 is a reboot of the reshape package. It's been over five years
since the first release of the package"..."reshape2 uses that knowledge to make a new package for reshaping data that is much more focused and much much faster."