read.dta {foreign}R Documentation

Read Stata Binary Files


Reads a file in Stata version 5-9 binary format into a data frame.


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


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 8,9 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.


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 introduced a system of 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.


a data frame


Thomas Lumley


Stata Users Manual (versions 5 & 6), Programming manual (version 7), or online help (version 8,9) describe the format of the files.

See Also

write.dta, attributes Date factor



[Package foreign version 0.8-20 Index]