Wide and narrow data
Introduction '''Wide''' and '''narrow''' (sometimes un-stacked and stacked, or wide and tall) are terms used to describe two different presentations for tabular data.
Wide Wide, or unstacked data is presented with each different data variable in a separate column. Person Age WeightHeight Bob 32 168180 Alice 24 150175 Steve 64 144165
Narrow :Narrow, stacked, or long data is presented with one column containing all the values and another column listing the context of the value Person Variable Value Bob Age 32 Bob Weight 168BobHeight180 Alice Age 24 Alice Weight 150AliceHeight175 Steve Age 64 Steve Weight 144SteveHeight165This is often easier to implement; addition of a new field does not require any changes to the structure of the table, however it can be harder for people to understand.
Implementations Many statistical and data processing systems have functions to convert between these two presentations, for instance the R programming language has several packages such as the  tidyr package. The pandas package in Python implements this operation as  "melt" function which converts a wide table to a narrow one. The process of converting a narrow table to wide table is generally referred to as "pivoting" in the context of data transformations. The "pandas" python package provides a  "pivot" method which provides for a narrow to wide transformation.
See also * Abstract data type* Pivot table* Table (information)* Information graphics* Row (database)* Table (database)* Table (HTML)
References
External links *  https://tidyr.tidyverse.org/articles/pivot.html*  https://cran.r-project.org/web/packages/reshape