ReadStat: Read data sets from R, SAS, Stata, and SPSS

Originally developed for Wizard, ReadStat is an MIT-licensed C library for reading files from popular stats packages. Supported formats include:

• R: RData and RDS
• SAS: SAS7BDAT and SAS7BCAT
• Stata: DTA
• SPSS: POR and SAV

There is also preliminary write support for the DTA and SAV formats.

The ReadStat API is callback-based. It uses very little memory, and is suitable for programs with progress bars. ReadStat uses iconv to automatically transcode text data into UTF-8, so you don't have to worry about character encodings.

Installation

Tweak the Makefile and then:

make
sudo make install

Usage

See src/readstat.h for the complete API. In general you'll provide a filename and a set of optional callback functions for handling various information and data found in the file. It's up to the user to store this information in an appropriate data structure. If a context pointer is passed to the parse_* functions, it will be made available to the various callback functions.

Callback functions should return 0 on success. Returning a non-zero value will abort the parsing process.

Example: Return the number of records in a DTA file.

#include "readstat.h"

int handle_info(int obs_count, int var_count, void *ctx) {
    int *my_count = (int *)ctx;

    *my_count = obs_count;

    return 0;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <filename>\n", argv[0]);
        return 1;
    }
    int my_count = 0;
    readstat_error_t error = READSTAT_OK;
    readstat_parser_t *parser = readstat_parser_init();
    readstat_set_info_handler(parser, &handle_info);

    error = readstat_parse_dta(parser, argv[1], &my_count);

    readstat_parser_free(parser);

    if (error != READSTAT_OK) {
        printf("Error processing %s: %d\n", argv[1], error);
        return 1;
    }
    printf("Found %d records\n", my_count);
    return 0;
}

Example: Convert a DTA to a tab-separated file.

#include "readstat.h"

int handle_info(int obs_count, int var_count, void *ctx) {
    int *my_var_count = (int *)ctx;
    
    *my_var_count = var_count;

    return 0;
}

int handle_variable(int index, readstat_variable_t *variable, 
    const char *val_labels, void *ctx) {
    int *my_var_count = (int *)ctx;

    printf("%s", readstat_variable_get_name(variable));
    if (index == *my_var_count - 1) {
        printf("\n");
    } else {
        printf("\t");
    }

    return 0;
}

int handle_value(int obs_index, int var_index, readstat_value_t value, void *ctx) {
    int *my_var_count = (int *)ctx;
    readstat_types_t type = readstat_value_type(value);
    if (!readstat_value_is_missing(value)) {
        if (type == READSTAT_TYPE_STRING) {
            printf("%s", readstat_string_value(value));
        } else if (type == READSTAT_TYPE_CHAR) {
            printf("%hhd", readstat_char_value(value));
        } else if (type == READSTAT_TYPE_INT16) {
            printf("%hd", readstat_int16_value(value));
        } else if (type == READSTAT_TYPE_INT32) {
            printf("%d", readstat_int32_value(value));
        } else if (type == READSTAT_TYPE_FLOAT) {
            printf("%f", readstat_float_value(value));
        } else if (type == READSTAT_TYPE_DOUBLE) {
            printf("%lf", readstat_double_value(value));
        }
    }
    if (var_index == *my_var_count - 1) {
        printf("\n");
    } else {
        printf("\t");
    }

    return 0;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <filename>\n", argv[0]);
        return 1;
    }
    int my_var_count = 0;
    readstat_error_t error = READSTAT_OK;
    readstat_parser_t *parser = readstat_parser_init();
    readstat_set_info_handler(parser, &handle_info);
    readstat_set_variable_handler(parser, &handle_variable);
    readstat_set_value_handler(parser, &handle_value);

    error = readstat_parse_dta(parser, argv[1], &my_var_count);

    readstat_parser_free(parser);

    if (error != READSTAT_OK) {
        printf("Error processing %s: %d\n", argv[1], error);
        return 1;
    }
    return 0;
}

Language Bindings

• Julia: DataRead.jl
• R: haven