Monday, 13 August 2018

Data Frames in R Programming

The commands c, cbind, vector and matrix functions combine data.

Another option is the data frame.

In a data frame, we can combine variables of equal length, which each row in the data frame containing observations on the same unit.

Hence, it is similar to the matrix or cbind functions.

Advantage is that one can make changes to the data without affecting the original data.

One can also combine numerical variables, character strings as well as factor in data frame.

For example, cbind and matrix functions can not be used to combine different types to data.

Data frames are special types of objects in R designed for data sets.

The data frame is similar to a spreadsheet, where columns contain variables and observations are contained in rows.

Data frames contain complete data sets that are mostly created with other programs (spreadsheet-files, software SPSS-files, Excel-files etc.).

Variables in a data frame may be numeric (numbers) or categorical (characters or factors).

Example :
Package "MASS" describes functions and data-sets to support Venables and Ripley, "Modern Applied Statistics with S" (4th edition 2002)

An example data frame Painters is available in the library.

MASS (here only an excerpt of a data set):

Here, the frames of the painters serve as row identifications, i.e.,
every row is assigned to the name of the corresponding painter.


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