Overview of DataFrames - Maple Programming Help

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Overview of DataFrames

 

Description

Indexing

Description

• 

A DataFrame is a two-dimensional data container, similar to a Matrix, but which can contain heterogeneous data, and for which symbolic names may be associated with the rows and columns.

Indexing

• 

Each column of a DataFrame is a DataSeries, and the column labels may be used to refer to the corresponding column.

df := DataFrame( < 1, 2, 3; 4, 5, 6 >, 'rows' = [ 'a', 'b' ], 'columns' = [ 'A', 'B', 'C' ] );

df:=ABCa123b456

(1)

type( df[ 'B' ], DataSeries );

true

(2)
• 

Since each column is a DataSeries, you can index hierarchically into the columns of a DataFrame to extract individual data elements.

df[ 'B' ][ 1 ];

2

(3)

df[ 'B' ][ 'b' ];

5

(4)
• 

However, you can also select individual data items by specifying the desired row and column indices directly.  (Row and column indices may be either numeric, by position, or symbolic.)

df[ 1, 2 ];

2

(5)

df[ 'a', 'B' ];

2

(6)
• 

You can use a range or list to select specified columns. In the case of a list, they can come in any desired order.

df[ 'A' .. 'B'];

ABa12b45

(7)

df[ [ 'B', 'C', 'A' ] ];

BCAa231b564

(8)
• 

For more information on indexing a DataFrame, see DataFrame,indexing.

Applications

Statistics with DataFrames

Subsets of DataFrames

See Also

A Guide to Data Frames

DataFrame/Constructor

DataFrame/indexing

DataSeries