Write Files in Stata Binary Format

Description

Writes the data frame to file in the Stata binary format. Does not write array variables unless they can be drop-ed to a vector.

Usage

write.dta(dataframe, file, version = 7L,
          convert.dates = TRUE, tz = "GMT",
          convert.factors = c("labels", "string", "numeric", "codes"))

Arguments

Details

The major differences between file formats in Stata versions is that version 7.0 and later allow 32-character variable names (5 and 6 were restricted to 8-character name). The abbreviate function is used to trim long variables to the permitted length. A warning is given if this is needed and it is an error for the abbreviated names not to be unique.

The columns in the data frame become variables in the Stata data set. Missing values are correctly handled.

Unless deselected, R date and date-time objects (POSIXt classes) are converted into the Stata format. For date-time objects this may lose information – Stata dates are in days since 1960-1-1. POSIXct objects can be written without conversion but will not be understood as dates by Stata; POSIXlt objects cannot be written without conversion.

There are four options for handling factors. The default is to use Stata value labels for the factor levels. With convert.factors="string", the factor levels are written as strings. With convert.factors="numeric" the numeric values of the levels are written, or NA if they cannot be coerced to numeric. Finally, convert.factors="codes" writes the underlying integer codes of the factors. This last used to be the only available method and is provided largely for backwards compatibility.

For Stata 8 or later use the default version=7 – the only advantage of Stata 8 format is that it can represent multiple different missing value types, and R doesn't have them. Stata 10 allows longer format lists, but R does not make use of them.

Note that the Stata formats are documented to be use ASCII strings – R does not enforce this, but use of non-ASCII character strings will not be portable as the encoding is not recorded.

Stata uses some large numerical values to represent missing values. This function does not currently check, and hence integers greater than 2147483620 and doubles greater than 8.988e+307 may be misinterpreted by Stata.

Value

NULL

Author(s)

Thomas Lumley

References

Stata 6.0 Users Manual, Stata 7.0 Programming manual, Stata 8.0, 9.0 online help describe the file formats.

See Also

read.dta, attributes, DateTimeClasses, abbreviate

Examples

write.dta(swiss, swissfile <- tempfile())
read.dta(swissfile)