XDataFrame-utils {IRanges} | R Documentation

## XDataFrame utility functions

### Description

Utility functions for manipulating `XDataFrame` objects.

### Usage

    ## S4 method for signature 'expressionORlanguage,
    ##   XDataFrame':
    eval(expr, envir, enclos = parent.frame())

### Arguments

`expr` | The `expression`, `call`, or `name` to be evaluated.
`envir` | The `XDataFrame` object in which to evaluate `expr`.
`enclos` | The `environment` in which to look for symbols that do not exist in the environment formed from `XDataFrame`.

### Details

The `eval` method converts the `XDataFrame` object specified in `envir` to an `environmnent`, with `enclos` as its parent, and then evaluates `expr` within that environment. As when evaluating within an ordinary `data.frame`, the environment formed from an `XDataFrame` contains a symbol for each column name which refers to the object stored in that column.

The objects are not actually copied into the environment. Rather, they are dynamically bound using `makeActiveBinding`. This prevents unnecessary copying of the data from the external vectors into R vectors. The values are cached, so that the data is not copied every time the symbol is accessed.

### Value

The result of expression evaluation.

### Author(s)

Michael Lawrence

### See Also

`FilterRules` objects, which can be evaluated on a `XDataFrame`, and the base `eval` function.

### Examples

      score <- c(10L, 2L, NA)
      rd <- XDataFrame(score)
      eval(quote(score > 3), rd)

[Package IRanges version 1.2.3 Index]