Data Frames

The DataFrame<R, C> class represents a data set that consists of multiple variables that may have different element types. The columns in a data frame are generic vectors. All columns have the same number of observations.

The rows and columns of a data frame can be accessed by position or by key. The collection of row keys or column keys is called an index. A data frame has a row index and a column index. Indexes were discussed in the previous section.

In this section:

• Constructing data frames How to create data frames.

• Basic Operations on Data Frames How to load data from and save data to external data sources like data bases, text files and other file formats.

• Vectors and matrices as data frames The interaction between data frames and vectors and matrices.