Here are a few pieces of sample code for testing your installation or to give you a sense of what code with Apophenia's tools looks like.
Two data streams
The sample program here is intended to show how one would integrate Apophenia into an existing program. For example, say that you are running a simulation of two different treatments, or say that two sensors are posting data at regular intervals. The goal is to gather the data in an organized form, and then ask questions of the resulting data set. Below, a thousand draws are made from the two processes and put into a database. Then, the data is pulled out, some simple statistics are compiled, and the data is written to a text file for inspection outside of the program. This program will compile cleanly with the sample Makefile .
#include <apop.h>
double process_one(gsl_rng *r){
return gsl_rng_uniform(r) * gsl_rng_uniform(r) ;
}
double process_two(gsl_rng *r){
return gsl_rng_uniform(r);
}
int main(){
apop_query("create table samples(iteration, process, value); begin;" );
for (int i=0; i<1000; i++){
double p1 = process_one(r);
double p2 = process_two(r);
apop_query("insert into samples values(%i, %i, %g);" , i, 1, p1);
apop_query("insert into samples values(%i, %i, %g);" , i, 2, p2);
}
apop_query("commit;" );
printf("\t mean\t\t var\n" );
printf("process 1: %f\t%f\n" , apop_mean(v1), apop_var(v1));
printf("process 2: %f\t%f\n\n" , apop_mean(v2), apop_var(v2));
printf("t test\n" );
apop_data_print(m, "the_data.txt" );
}
int apop_table_exists(char const *name, char remove)
Definition apop_db.c:132
int apop_db_open(char const *filename)
Definition apop_db.c:86
apop_data * apop_db_to_crosstab(char const *tabname, char const *row, char const *col, char const *data, char is_aggregate)
Definition apop_conversions.c:126
#define Apop_cv(data_to_view, col)
Definition docs/include/apop.h:1328
gsl_rng * apop_rng_alloc(int seed)
Definition apop_bootstrap.c:19
apop_data * apop_t_test(gsl_vector *a, gsl_vector *b)
Definition apop_tests.c:55
Definition docs/include/apop.h:72
Run a regression
See A quick overview for an example of loading a data set and running a simple regression.
A sequence of t-tests
In The section on map/apply , a new -test on every row, with all operations acting on entire rows rather than individual data points:
#include <apop.h>
double row_offset;
void offset_rng(double *v){*v = gsl_rng_uniform(apop_rng_get_thread()) + row_offset;}
double find_tstat(gsl_vector *in){ return apop_mean(in)/sqrt(apop_var(in));}
double conf(double in, void *df){ return gsl_cdf_tdist_P(in, *(int *)df);}
int main(){
for (int i=0; i< 10; i++){
row_offset = gsl_rng_uniform(r)*2 -1;
}
int df = d->matrix->size2-1;
apop_data *means = apop_map(d, .fn_v = mu, .part =
'r' );
apop_data *tstats = apop_map(d, .fn_v = find_tstat, .part =
'r' );
apop_data *confidences = apop_map(tstats, .fn_dp = conf, .param = &df);
printf("means:\n" ); apop_data_show(means);
printf("\nt stats:\n" ); apop_data_show(tstats);
printf("\nconfidences:\n" ); apop_data_show(confidences);
for (int i=0; i< 10; i++){
assert(fabs(gsl_cdf_tdist_Pinv(
apop_data_get (confidences, i, -1), 99)
}
}
double apop_data_get(const apop_data *data, size_t row, int col, const char *rowname, const char *colname, const char *page)
Definition apop_data.c:841
#define Apop_rv(data_to_view, row)
Definition docs/include/apop.h:1303
void apop_vector_apply(gsl_vector *v, void(*fn)(double *))
Definition apop_mapply.c:390
double apop_vector_mean(gsl_vector const *v, gsl_vector const *weights)
Definition apop_stats.c:521
apop_data * apop_data_alloc(const size_t size1, const size_t size2, const int size3)
Definition apop_data.c:34
In the documentation for apop_query_to_text, a program to list all the tables in an SQLite database.
#include <apop.h>
void print_table_list(char *db_file){
apop_data *tab_list= apop_query_to_text(
"select name "
"from sqlite_master where type=='table'" );
for (int i=0; i< tab_list->textsize[0]; i++)
printf("%s\n" , tab_list->text[i][0]);
}
int main(int argc, char **argv){
if (argc == 1){
printf("Give me a database name, and I will print out "
"the list of tables contained therein.\n" );
return 0;
}
print_table_list(argv[1]);
}
Marginal distribution
A demonstration of fixing parameters to create a marginal distribution, via apop_model_fix_params
#include <apop.h>
int main(){
size_t ct = 5e4;
apop_data *params = apop_data_falloc((2,2,2), 8, 1, 0.5,
2, 0.5, 1);
pvm->dsize = 2;
gsl_vector_set_all(pvm->parameters->vector, GSL_NAN);
printf("original params: " );
apop_vector_print(params->vector);
printf("estimated params: " );
apop_vector_print(e1->parameters->vector);
}
apop_model * apop_model_copy(apop_model *in)
Definition apop_model.c:163
apop_model * apop_model_fix_params(apop_model *model_in)
Definition apop_fix_params.c:232
double apop_vector_distance(const gsl_vector *ina, const gsl_vector *inb, const char metric, const double norm)
Definition apop_stats.c:221
apop_data * apop_data_copy(const apop_data *in)
Definition apop_data.c:295
apop_data * apop_model_draws(apop_model *model, int count, apop_data *draws)
Definition apop_asst.c:421
apop_model * apop_estimate(apop_data *d, apop_model *m)
Definition apop_model.c:237
apop_multivariate_normal
Definition model_doc.h:423
Definition docs/include/apop.h:98