Tidy data is a term that was coined in a paper named "Tidy Data" by Hadley Wickham. I highly recommend that you read this paper. It can be downloaded from http://vita.had.co.nz/papers/tidy-data.pdf.
The paper covers many details of the process of creating tidy data, the end result of which is that you have data that is free of surprises and is ready for analysis.
We will examine many of the tools in pandas for tidying your data. These exist because we need to handle the following situations:
- The names of the variables are different from what you require
- There is missing data
- Values are not in the units that you require
- The period of sampling of records is not what you need
- Variables are categorical and you need quantitative values
- There is noise in the data
- Information is of an incorrect type
- Data is organized around incorrect axes
- Data is...
