How to group rows with the same column value into one row in C?-CodePudding

I am trying to make a statistic calculation code where a file with years are given on column1, type is given on column2 and count is given for column3. And finding the sum of counts for each type for each year.

I am stuck on grouping my data with same value in the column to be in the same row..

Input data:

2010    101     22
2010    101     40
2010    101     44
2010    101     66
2010    102     14
2010    100     7
2010    101     2
2010    101     3
2010    101     2
2010    101     3
2011    101     23
2011    101     27
2011    101     47
2011    101     66
2011    100     5
2011    102     16
2011    101     4
2011    101     1
2011    101     3
2011    101     5

Output:

| Year | 100 | 101 | 102 |
--------------------------
| 2010 |  7  | 182 |  14 |
| 2011 |  5  | 176 |  16 |

I could do

if(year == 2010)
{}
if(year == 2011)
{}

but my data is not going to always be like the given input. Is there a way to group them without knowing how many rows and what is going to be given in the year column? Maybe comparing row by row?

I'm confused, please help..

CodePudding user response：

With a fixed/limited range for years and types, we can used a fixed size 2D array to hold the counts.

Here's some code that does that:

#include <stdio.h>
#include <stdlib.h>

// year config
#define YRLO    2008
#define YRHI    2020
#define YRTOT   ((YRHI - YRLO)   1)

// type config
#define TYPLO   100
#define TYPHI   103
#define TYPTOT  ((TYPHI - TYPLO)   1)

#define RANGE(_val,_lo,_hi) \
    ((_val) >= (_lo)) && ((_val) <= (_hi))

int counts[YRTOT][TYPTOT];

int
main(void)
{

    const char *file = "data.txt";
    FILE *xfin = fopen(file,"r");

    if (xfin == NULL) {
        perror(file);
        exit(1);
    }

    int yr;
    int typ;
    int cnt;
    int lno = 0;

    while (fscanf(xfin,"%d %d %d",&yr,&typ,&cnt) == 3) {
          lno;

        if (! RANGE(yr,YRLO,YRHI)) {
            printf("line %d -- bad year -- %d\n",lno,yr);
            continue;
        }

        if (! RANGE(typ,TYPLO,TYPHI)) {
            printf("line %d -- bad type -- %d\n",lno,typ);
            continue;
        }

        // store data (convert absolute years and types to relative numbers)
        counts[yr - YRLO][typ - TYPLO]  = cnt;
    }

    fclose(xfin);

    const char *fmt = " |