STATAMOD

STATAMOD is a Fortran module that provides read/write access for Stata datasets from within Fortran. It is written by Andrew Shephard (asheph@econ.upenn.edu)

Stata read support

The reading of variables from a Stata .dta file is supported through the following subroutines and functions.

subroutine openStata(filename [, cache])

This opens the Stata .dta file filename. A dataset must be open before any other (reading) STATAMOD commands can be used. By default, the entire dataset is loaded into memory (cache=.true.). If you specify openStata(filename, cache = .false.) then it will not do this. Instead, it will just load the variables as requested from disk. As variables are stored non-sequentially in the Stata .dta format, this can be significantly slower than memory access.

subroutine descStata()

This describes the open dataset, printing output to the standard output unit. It is much like Stata's own describe command.

integer function nobsStata()

Returns an integer equal to the number of observations in the open dataset.

integer function nvarStata()

Returns an integer equal to the number of variables in the open dataset.

logical function existStata(varname)

Returns .true. or .false. depending on whether the variable exists in the open dataset.

subroutine readStata(readStataVar,varname)

Copies data from the Stata variable varname in the open dataset to readStataVar. If nobsStata exceeds the dimension of readStataVar an error is raised. Otherwise the data is copied to first nobsStata elements of readStataVar.

subroutine closeOpenStata()

Closes the open Stata dataset. Call this procedure after all the relevant data has been read. This will close the file connected to the specified unit or free memory used to temporarily store the dataset depending upon whether disk or memory (default) mode was specified in the openStata() subroutine.

Stata read support example

An example of typical STATAMOD usage is provided below.

use statamod

implicit none

integer, parameter :: dp = selected_real_kind(15, 100)
integer :: nObs

real(dp),  dimension(:),    allocatable :: hhincome
real(dp),  dimension(:, :), allocatable :: hours

call openStata('statafile.dta')
call descStata()

nObs = nobsStata()
allocate(hhincome(nObs))
allocate(hours(nObs, 2))

call readStata(hhincome, 'income')
call readStata(hours(:, 1), 'hours_male')
call readStata(hours(:, 2), 'hours_female')

call closeOpenStata()

Stata write support

There are a small number of subroutines that provide Stata .dta write functionality.

subroutine saveStata(fileName, obs [, label])

This opens the Stata .dta file filename for saving. You must specify the number of observations obs to save (saving is on a variable by variable basis), and you can optionaly specify a label for the dataset. It will save the dataset in the Stata 7 SE file format.

subroutine writeStata(thisVar, thisName [, thisLabel])

Saves the Fortran variable thisVar with the Stata variable name thisName. You can optionally label the variable with thisLabel. You should call writeStata for every variable you wish to save.

subroutine closeSaveStata()

Closes the open saveStata dataset. The file will only be written when this routine is called.

Further information

If you receive a stack overflow error when using the subroutine readStata() increase the stack size, or specify cache=.false. in the calling options. This may happen with large data sets.

STATAMOD should be able to read Stata .dta files for versions 5 to 12. I have not been able to test data created with Stata version 5 or 6 and neither do I have a detailed description of the file format implemented in these versions. Please contact me if such datasets produces any unexpected results. Support for Stata .dta files for version 13 and above will be provided in a future release.

Software license

STATAMOD is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

STATAMOD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with STATAMOD. If not, see http://www.gnu.org/licenses/.