R: Data Input from Spreadsheet

read.DIF {utils}

R Documentation

Data Input from Spreadsheet

Description

Reads a file in Data Interchange Format (DIF) and creates a data frame from it. DIF is a format for data matrices such as single spreadsheets.

Usage

read.DIF(file, header = FALSE, 
           dec = ".", row.names, col.names,
           as.is = !stringsAsFactors,
           na.strings = "NA", colClasses = NA, nrows = -1,
           skip = 0, check.names = TRUE, 
           blank.lines.skip = TRUE,
           stringsAsFactors = default.stringsAsFactors())

Arguments

`file`	the name of the file which the data are to be read from, or a connection, or a complete URL.
`header`	a logical value indicating whether the spreadsheet contains the names of the variables as its first line. If missing, the value is determined from the file format: `header` is set to `TRUE` if and only if the first row contains only character values and the top left cell is empty.
`dec`	the character used in the file for decimal points.
`row.names`	a vector of row names. This can be a vector giving the actual row names, or a single number giving the column of the table which contains the row names, or character string giving the name of the table column containing the row names. If there is a header and the first row contains one fewer field than the number of columns, the first column in the input is used for the row names. Otherwise if `row.names` is missing, the rows are numbered. Using `row.names = NULL` forces row numbering.
`col.names`	a vector of optional names for the variables. The default is to use `"V"` followed by the column number.
`as.is`	the default behavior of `read.DIF` is to convert character variables (which are not converted to logical, numeric or complex) to factors. The variable `as.is` controls the conversion of columns not otherwise specified by `colClasses`. Its value is either a vector of logicals (values are recycled if necessary), or a vector of numeric or character indices which specify which columns should not be converted to factors. Note: to suppress all conversions including those of numeric columns, set `colClasses = "character"`. Note that `as.is` is specified per column (not per variable) and so includes the column of row names (if any) and any columns to be skipped.
`na.strings`	a character vector of strings which are to be interpreted as `NA` values. Blank fields are also considered to be missing values in logical, integer, numeric and complex fields.
`colClasses`	character. A vector of classes to be assumed for the columns. Recycled as necessary, or if the character vector is named, unspecified values are taken to be `NA`. Possible values are `NA` (when `type.convert` is used), `"NULL"` (when the column is skipped), one of the atomic vector classes (logical, integer, numeric, complex, character, raw), or `"factor"`, `"Date"` or `"POSIXct"`. Otherwise there needs to be an `as` method (from package methods) for conversion from `"character"` to the specified formal class. Note that `colClasses` is specified per column (not per variable) and so includes the column of row names (if any).
`nrows`	the maximum number of rows to read in. Negative values are ignored.
`skip`	the number of lines of the data file to skip before beginning to read data.
`check.names`	logical. If `TRUE` then the names of the variables in the data frame are checked to ensure that they are syntactically valid variable names. If necessary they are adjusted (by `make.names`) so that they are, and also to ensure that there are no duplicates.
`blank.lines.skip`	logical: if `TRUE` blank lines in the input are ignored.
`stringsAsFactors`	logical: should character vectors be converted to factors?

Value

A data frame (data.frame) containing a representation of the data in the file. Empty input is an error unless col.names is specified, when a 0-row data frame is returned: similarly giving just a header line if header = TRUE results in a 0-row data frame.

Note

The columns referred to in as.is and colClasses include the column of row names (if any).

Less memory will be used if colClasses is specified as one of the six atomic vector classes.

References

The DIF format specification can be found by searching on http://www.wotsit.org/; the optional header fields are ignored. See also http://en.wikipedia.org/wiki/Data_Interchange_Format.

The term is likely to lead to confusion: Windows will have a ‘Windows Data Interchange Format (DIF) data format’ as part of its WinFX system, which may or may not be compatible.