lsgxeva / readstat

C library for reading files from popular stats packages (Stata, SPSS, R...)

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

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

The API is callback-based and is suitable for programs with progress bars.

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;
    int error = parse_dta(argv[1], &my_count, &handle_info, NULL, NULL, NULL);
    if (error != 0) {
        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, const char *var_name, const char *var_format, const char *var_label, 
    const char *val_labels, readstat_types_t type, size_t max_len, void *ctx) {
    int *my_var_count = (int *)ctx;

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

    return 0;
}

int handle_value(int obs_index, int var_index, void *value, readstat_types_t type, void *ctx) {
    int *my_var_count = (int *)ctx;
    if (value != NULL) {
        if (type == READSTAT_TYPE_STRING) {
            printf("%s", (char *)value);
        } else if (type == READSTAT_TYPE_CHAR) {
            printf("%hhd", *(char *)value);
        } else if (type == READSTAT_TYPE_INT16) {
            printf("%hd", *(short *)value);
        } else if (type == READSTAT_TYPE_INT32) {
            printf("%d", *(int *)value);
        } else if (type == READSTAT_TYPE_FLOAT) {
            printf("%f", *(float *)value);
        } else if (type == READSTAT_TYPE_DOUBLE) {
            printf("%lf", *(double *)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;
    int error = parse_dta(argv[1], &my_var_count, &handle_info, &handle_variable, &handle_value, NULL);
    if (error != 0) {
        printf("Error processing %s: %d\n", argv[1], error);
        return 1;
    }
    return 0;
}