R: Small (Helper) Functions

small-helpers {collapse} | R Documentation

## Small (Helper) Functions

### Description

Convenience functions in the collapse package that help to deal with object attributes such as variable names and labels, matching and object checking, and that improve the workflow.

### Usage

    .c(...)                       # Non-standard concatenation i.e. .c(a, b) == c("a", "b")
    nam %=% values                # Multiple-assignment e.g. .c(x, y) %=% c(1, 2),
    massign(nam, values,          # can also assign to different environment.
            envir = parent.frame())
    vlabels(X, attrn = "label",   # Get labels of variables in X, in attr(X[[i]], attrn)
            use.names = TRUE)
    vlabels(X, attrn = "label") <- value    # Set labels of variables in X (by reference)
    setLabels(X, value, attrn = "label",    # Set labels of variables in X (by reference)
              cols = NULL)                  # and return X
    vclasses(X, use.names = TRUE) # Get classes of variables in X
    namlab(X, class = FALSE,      # Return data frame of names and labels,
      attrn = "label", N = FALSE, # and (optionally) classes, number of observations
      Ndistinct = FALSE)          # and number of non-missing distinct values
    add_stub(X, stub, pre = TRUE, # Add a stub (i.e. prefix or postfix) to column names
             cols = NULL)
    rm_stub(X, stub, pre = TRUE,  # Remove stub from column names, also supports general
            regex = FALSE,        # regex matching and removing of characters
            cols = NULL, ...)
    x %!in% table                 # The opposite of %in%
    ckmatch(x, table,             # Check-match: throws an informative error if non-matched
         e = "Unknown columns:")
    all_identical(...)            # Check exact equality of multiple objects or list-elements
    all_obj_equal(...)            # Check near equality of multiple objects or list-elements
    setRownames(object,
     nm = if(is.atomic(object))   # Set rownames of object and return object
     seq_row(object) else NULL)
    setColnames(object, nm)       # Set colnames of object and return object
    setDimnames(object, dn,
                which = NULL)     # Set dimension names of object and return object
    unattrib(object)              # Remove all attributes from object
    setAttrib(object, a)          # Replace all attributes with list of attributes 'a'
    copyAttrib(to, from)          # Copy all attributes from object 'from' to object 'to'
    copyMostAttrib(to, from)      # Copy most attributes from object 'from' to object 'to'
    is_categorical(x)             # The opposite of is.numeric
    is_date(x)                    # Check if object is of class "Date", "POSIXlt" or "POSIXct"

### Arguments

`X` | a matrix or data frame (some functions also support vectors and arrays although that is less common).
`x, table` | a (atomic) vector.
`object, to, from` | a suitable R object.
`a` | a suitable list of attributes.
`attrn` | character. Name of attribute to store labels or retrieve labels from.
`N, Ndistinct` | logical. Options to display the number of observations or number of distinct non-missing values.
`value` | for `whichv` and `alloc`: a single value of any vector type. For `vlabels<-` and `setLabels`: a matching character vector or list of variable labels.
`use.names` | logical. Preserve names if `X` is a list.
`cols` | integer. (optional) indices of columns to apply the operation to. Note that for these small functions this needs to be integer, whereas for other functions in the package this argument is more flexible.
`class` | logical. Also show the classes of variables in X in a column?
`stub` | a single character stub, i.e. "log.", which by default will be pre-applied to all variables or column names in X.
`pre` | logical. `FALSE` will post-apply `stub`.
`regex` | logical. Match pattern anywhere in names using a regular expression and remove it with `gsub`.
`nm` | a suitable vector of row- or column-names.
`dn` | a suitable vector or list of names for dimension(s).
`which` | integer. If `NULL`, `dn` has to be a list fully specifying the dimension names of the object. Alternatively, a vector or list of names for dimensions `which` can be supplied. See Examples.
`e` | the error message thrown by `ckmatch` for non-matched elements. The message is followed by the comma-separated non-matched elements.
`nam` | character. A vector of object names.
`values` | a matching atomic vector or list of objects.
`envir` | the environment to assign into.
`...` | for `.c`: Comma-separated expressions. For `all_identical / all_obj_equal`: Either multiple comma-separated objects or a single list of objects in which all elements will be checked for exact / numeric equality. For `rm_stub`: further arguments passed to `gsub`.

### Details

`copyAttrib` and `copyMostAttrib` take a shallow copy of the attribute list, i.e. they don't duplicate in memory the attributes themselves. They also, along with `setAttrib`, take a shallow copy of lists passed to the `to` argument, so that lists are not modified by reference. Atomic `to` arguments are however modified by reference.

`copyMostAttrib` copies all attributes except for `"names"`, `"dim"` and `"dimnames"` (like the corresponding C-API function), and further only copies the `"row.names"` attribute of data frames if known to be valid. Thus it is a suitable choice if objects should be of the same type but are not of equal dimensions.

### See Also

Efficient Programming, Collapse Overview

### Examples

    ## Non-standard concatenation
    .c(a, b, "c d", e == f)

    ## Multiple assignment
    .c(a, b) %=% list(1, 2)
    .c(T, N) %=% dim(EuStockMarkets)
    names(iris) %=% iris
    list2env(iris)          # Same thing
    rm(list = c("a", "b", "T", "N", names(iris)))

    ## Variable labels
    namlab(wlddev)
    namlab(wlddev, class = TRUE, N = TRUE, Ndistinct = TRUE)
    vlabels(wlddev)
    vlabels(wlddev) <- vlabels(wlddev)

    ## Stub-renaming
    log_mtc <- add_stub(log(mtcars), "log.")
    head(log_mtc)
    head(rm_stub(log_mtc, "log."))
    rm(log_mtc)

    ## Setting dimension names of an object
    head(setRownames(mtcars))
    ar <- array(1:9, c(3,3,3))
    setRownames(ar)
    setColnames(ar, c("a","b","c"))
    setDimnames(ar, c("a","b","c"), which = 3)
    setDimnames(ar, list(c("d","e","f"), c("a","b","c")), which = 2:3)
    setDimnames(ar, list(c("g","h","i"), c("d","e","f"), c("a","b","c")))

    ## Checking exact equality of multiple objects
    all_identical(iris, iris, iris, iris)
    l <- replicate(100, fmean(num_vars(iris), iris$Species), simplify = FALSE)
    all_identical(l)
    rm(l)

[Package collapse version 1.8.6 Index]