read.dta {foreign} | R Documentation

## Read Stata Binary Files

### Description

Reads a file in Stata version 5-8 or 7/SE binary format into a data frame.

### Usage

    read.dta(file, convert.dates = TRUE, tz = NULL,
             convert.factors = TRUE, missing.type = FALSE,
             convert.underscore=TRUE, warn.missing.labels=TRUE)

### Arguments

`file` | a filename as a character string.
`convert.dates` | Convert Stata dates to `Date` class?
`tz` | Previously used to specify time zone. Now deprecated.
`convert.factors` | Use Stata value labels to create factors? (version 6.0 or later).
`missing.type` | For version 8 only, store information about different types of missing data?
`convert.underscore` | Convert `"_"` in Stata variable names to `"."` in R names?
`warn.missing.labels` | Warn if a variable is specified with value labels and those value labels are not present in the file.

### Details

The variables in the Stata data set become the columns of the data frame. Missing values are correctly handled. The data label, variable labels, and timestamp are stored as attributes of the data frame. Nothing is done with variable characteristics.

Optionally, Stata dates (%d formats) are converted to R's `Date` class and variables with Stata value labels are converted to factors. Ordinarily, `read.dta` will not convert a variable to a factor unless a label is present for every level. Use `convert.factors=NA` to override this. In any case the value label and format information is stored as attributes on the returned data frame.

Stata 8.0 has 27 different missing data values. If `missing.type` is `TRUE` a separate list is created with the same variable names as the loaded data. For string variables the list value is `NULL`. For other variables the value is `NA` where the observation is not missing and 0-26 when the observation is missing. This is attached as the code{"missing"} attribute of the returned value.

The option to allow underscores in variable names may become the default in future versions now that R supports their use.

### Value

a data frame

### Author(s)

Thomas Lumley

### References

Stata Users Manual (versions 5 & 6), Programming manual (version 7), or online help (version 8) describe the format of the files.

### See Also

`write.dta`, `attributes` `Date` `factor`

### Examples

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

[Package foreign version 0.8-15 Index]