This chapter introduced the theoretical framework for reshaping a dataset. The limitations of conventional approaches were pointed out and the new paradigm of data layout was highlighted. In the new paradigm, only two functions allow users to rearrange datasets into various layouts as required. This chapter also discussed structural missing and sampling zero, and how to deal with those missing during the melting process. For faster and large data rearrangement, readers were redirected to the
reshape2 package. In the next chapter, we will discuss how R can be connected with databases and handle large-scale data.