C API about dataframe HOT 6 CLOSED

enum	Alx_DataFrame_Type {
	ALX_DF_S64 = 1,
	ALX_DF_DBL,
	ALX_DF_STR
};

struct	Alx_DataFrame_Cell {
	union {
		int64_t			z;
		double			r;
		struct Alx_DynBuf	*s;
	};
	int	err;
};

struct	Alx_DataFrame_Row {
	struct Alx_LinkedList	*cells;
	int			err;
};

union	Alx_DataFrame_Desc {
	struct	Alx_DataFrame_Desc_Txt {
		int	uniq;
		int	top;
		int	freq;
	};
	struct	Alx_DataFrame_Desc_Num {
		double	mean;
		double	std;
		double	min;
		double	q_25;
		double	q_50;
		double	q_75;
		double	max;
	};
};

struct	Alx_DataFrame_Col {
	int				type;   /* enum Alx_DataFrame_Type */
	struct Alx_DynBuf		*hdr;   /* column header string */
	cmp_f				*cmp;   /* user custom comparison function for the data (if not, standard comparations are done */
	bool				ltd_values;   /* limited set of possible values? */
	struct Alx_BST			*values;   /* values; either stored by the parser, or passed by the user if limited set of values is true */
	struct Alx_DataFrame_Desc	*desc;
};

struct	Alx_DataFrame {
	struct Alx_LinkedList	*cols;
	struct Alx_LinkedList	*rows;
};

int	alx_df_init		(struct Alx_DataFrame **df);
void	alx_df_deinit		(struct Alx_DataFrame *df);
int	alx_df_add_col		(struct Alx_DataFrame *restrict df,
				 int type, char *restrict hdr,
				 cmp_f *cmp,
				 struct Alx_BST *restrict values);
int	alx_df_parse		(struct Alx_DataFrame *restrict df,
				 FILE *restrict istream);
int	alx_df_drop_row		(struct Alx_DataFrame *df,
				 ptrdiff_t nrow);
int	alx_df_drop_col		(struct Alx_DataFrame *df,
				 ptrdiff_t ncol);
int	alx_df_dropna		(struct Alx_DataFrame *df);
int	alx_df_sort		(struct Alx_DataFrame *df,
				 ptrdiff_t ncol);
int	alx_df_sort_bwd		(struct Alx_DataFrame *df,
				 ptrdiff_t ncol);
int	alx_df_describe		(struct Alx_DataFrame *df);
int	alx_df_fprn_data	(FILE *restrict ostream,
				 struct Alx_DataFrame *restrict df);
int	alx_df_fprn_desc	(FILE *restrict ostream,
				 struct Alx_DataFrame *restrict df);

enum Fields {
	FLDS_ID,
	FLDS_NAME,
	FLDS_AGE,
	FLDS_HEIGHT,

	FIELDS
};
const char *const hdrs[FIELDS] = {
	[FLDS_ID]	= "id",
	[FLDS_NAME]	= "name",
	[FLDS_AGE]	= "age",
	[FLDS_HEIGHT]	= "height"
};
const char *const types[FIELDS] = {
	[FLDS_ID]	= ALX_DF_S64,
	[FLDS_NAME]	= ALX_DF_STR,
	[FLDS_AGE]	= ALX_DF_S64,
	[FLDS_HEIGHT]	= ALX_DF_DBL
};

int main(void)
{
	struct Alx_DataFrame	*df;
	FILE			*less;

	fp = fopen("file.csv", "r");

	alx_df_init(&df);
	for (ptrdiff_t i = 0; i < FIELDS; i++)
		alx_df_add_col(df, types[i], hdrs[i], NULL, NULL);
	alx_df_parse(df, fp);

	alx_sort_bwd(FLDS_AGE);		/* oldest first */
	less	= popen("less -S", "w");
	alx_df_fprn_data(less, df);	/* print data with less(1) */
	pclose(less);

	alx_df_describe(df);		/* calculate description */
	less	= popen("less -S", "w");
	alx_df_fprn_desc(less, df);	/* print description with less(1) */
	pclose(less);

	alx_df_dropna(df);		/* drop rows with invalid values */
	less	= popen("less -S", "w");
	alx_df_fprn_data(less, df);	/* print data with less(1) */
	pclose(less);
	alx_df_describe(df);		/* need to calculate description again */
	less	= popen("less -S", "w");
	alx_df_fprn_desc(less, df);	/* print description with less(1) */
	pclose(less);


	return	0;
}