ApplyToRows - Maple Help

DataSets[Builtin][Reference]

 ApplyToRows
 create a Matrix of transformed data with algebraic expressions

 Calling Sequence ApplyToRows(ref, aexp1, aexp2, ..., aexpN)

Parameters

 ref - reference to built-in data aexp1, aexp2, ..., aexpN - algebraic expressions where the indeterminants are column names of ref as Maple names

Description

 • The ApplyToRows command creates Matrix of transformed data.
 • The number of columns is equal to the number of algebraic expressions. The number of rows is equal to the number of rows in ref.
 • The value of the $i,j$-th entry is the $j$-th algebraic expression evaluated with the column names substituted for the values in those columns in the $i$-th row of ref.
 • Time series data in the reference object are treated as their newest value when using this command.

Examples

 > $\mathrm{with}\left(\mathrm{DataSets}\right):$
 > $\mathrm{ref}≔\mathrm{Reference}\left("Builtin","Country"\right)\left[\left["Canada","USA"\right],\left["Airports","Heliports"\right]\right]$
 ${\mathrm{ref}}{≔}\left[\begin{array}{ccc}{\mathrm{Country \left(Name\right)}}& {\mathrm{Airports}}& {\mathrm{Heliports}}\\ {\mathrm{Canada}}& {1467}& {26}\\ {\mathrm{USA}}& {13513}& {5287}\end{array}\right]$ (1)

Find the airport to heliport ratio in Canada and the USA

 > $\mathrm{ApplyToRows}\left(\mathrm{ref}\left[\left["Canada","USA"\right]\right],\frac{\mathrm{Airports}}{\mathrm{Heliports}}\right)$
 $\left[\begin{array}{c}\frac{{1467}}{{26}}\\ \frac{{13513}}{{5287}}\end{array}\right]$ (2)

To also have the absolute number of airports in the first column

 > $\mathrm{ApplyToRows}\left(\mathrm{ref}\left[\left["Canada","USA"\right]\right],\mathrm{Airports},\frac{\mathrm{Airports}}{\mathrm{Heliports}}\right)$
 $\left[\begin{array}{cc}{1467}& \frac{{1467}}{{26}}\\ {13513}& \frac{{13513}}{{5287}}\end{array}\right]$ (3)

Compatibility

 • The DataSets[Builtin][Reference][ApplyToRows] command was introduced in Maple 2015.