# Looping and Iteration

These are the available functions for looping and iteration. See each function's help topic in the TERR Language Reference for more information.

Function name | Title description
--- | ---
`(` | The Structure of Expressions
`{` | The Structure of Expressions
`||` | Control Flow
`aggregate` | Compute Summary Statistics of Subsets of Data
`aggregate.data.frame` | Compute Column-by-Column Summaries of Groups of Observations
`aggregate.default` | Compute Summary Statistics of Subsets of Data
`aggregate.formula` | Compute Summary Statistics of Subsets of Data
`aggregate.ts` | Compute Summary Statistics of Subsets of Data
`apply` | Apply a Function to Sections of an Array
`break` | Control Flow
`by` | Split a Data Frame and Apply a Function to the Parts
`by.data.frame` | Split a Data Frame and Apply a Function to the Parts
`by.default` | Split a Data Frame and Apply a Function to the Parts
`colMeans` | Row and Column Summaries
`colSums` | Row and Column Summaries
`Control` | Control Flow
`dendrapply` | Apply a Function to All Nodes of a Dendrogram
`eapply` | Apply a Function Over Values in an Environment
`else` | Control Flow
`for` | Control Flow
`function` | The Structure of Expressions
`if` | Control Flow
`in` | Control Flow
`lapply` | Apply a Function to Components of a List or Vector
`next` | Control Flow
`rapply` | Apply a Function Recursively
`repeat` | Control Flow
`return` | The Structure of Expressions
`rowMeans` | Row and Column Summaries
`rowsum` | Group Row Sums of a Matrix
`rowsum.default` | Group Row Sums of a Matrix
`rowSums` | Row and Column Summaries
`sapply` | Apply a Function to Components of a List or Vector
`simplify2array` | Apply a Function to Components of a List or Vector
`sweep` | Sweep Out Array Summaries
`Syntax` | The Structure of Expressions
`tapply` | Apply a Function to a Ragged Array
`vapply` | Apply a Function to Components of a List or Vector
`while` | Control Flow