CODEWITHSUNDEEP
c
green
green

Reputation: 713

Detecting Increasing or Decreasing Data

I got a data file which consists of a single column with the header name with temperature and the following rows are just a series of recorded temperature. I can read it successfully(perhaps) into the C program using the following command:

#include <stdio.h>
#include <cstdlib>

int main()
{
FILE *fpt;  /*define a pointer to predefined structure type FILE*/

    fpt = fopen("temperature.dat","r");

char temp[10];
float t[7];
int i;

fscanf(fpt, "%s",temp);
printf("%s",temp);

for(i=0;i<7;++i)
{
    fscanf(fpt, "%f",&t[i]);
    printf("%.2f",t[i]);
}

printf("%f",t[3]);  /*just testing whether the program is reading correctly*/

fclose(fpt);
system("pause");
}

But the problem is how could I detect when there is a series of temperature, for instance 6 temperature values are increasing continuously. I need something like IF total of 6 values of temperature is increased continuously, then it will generate some error message using printf function. Assume that the total input number of data is not fixed, how could I program it.

Upvotes: 0

Views: 459

Answers (5)

imran
imran

Reputation: 1560

You will need some kind of counter to see how many times you have seen incrementing temperatures. Also, read the file in a while loop:

#include <stdio.h>

int main()
{
    FILE *fpt;  /*define a pointer to predefined structure type FILE*/

    fpt = fopen("temperature.dat","r");

    char temp[10];
    int count = 0;
    int i;
    float prev_temp = -999.00;
    float current_temp;
    int threshold = 6;

    fscanf(fpt, "%s",temp); // header?
    printf("Header: %s\n",temp);

    while(!feof(fpt)) {
        fscanf(fpt, "%f", &current_temp);
        if (current_temp > prev_temp) count++;
        else count = 0;
        prev_temp = current_temp;
        if (count > threshold) printf("Saw %d consecutive increases\n", count);
    }

    fclose(fpt);
}

Upvotes: 0

JohnH
JohnH

Reputation: 2721

Add a variable (say, inctemp) to count seeing increases in a row, and increment it in your loop if there is an increase. Reset it to 0 if there is not an increase. At the end of your loop, you know how many in a row there were (at least at the end of the data set)

Modified for arbitrary number of reads

int inctemp = 0;
float curtemp, prevtemp;

...

if ( fscanf(fpt, "%f",&prevtemp) == 1)
    printf("%.2f",prevtemp);
    while( fscanf(fpt, "%f",&curtemp) == 1)
    {
        printf("%.2f",curtemp);
        if( curtemp > prevtemp ) {
            inctemp++;
        } 
        else {
            inctemp = 0;
        }
        if( inctemp == 6 ) {
            printf("Six increases in a row!\n");
        }
        prevtemp = curtemp;
  }
}

Upvotes: 0

ooga
ooga

Reputation: 15501

To detect whether a file of floats has at least 6 increasing values in a row, you could do something like this:

#include <stdio.h>

#define IN_A_ROW 6

int main() {
  FILE *f = fopen("temps.txt", "r");
  float x, last_x;
  int inc = 0;
  fscanf(f, "%f", &last_x);
  while (fscanf(f, "%f", &x) == 1) {
    if (x > last_x) {   // or maybe >=
      if (++inc >= IN_A_ROW) {
        printf("Found %d increases in a row\n", IN_A_ROW);
        return -1;
      }
    }else
      inc = 0;
    last_x = x;
  }
  fclose(f);
  return 0;
}

Upvotes: 1

Aret
Aret

Reputation: 475

Finding a delta between the temperatures will help you.

#include <stdio.h>
#include <cstdlib>

int main()
{
    FILE *fpt;  /*define a pointer to predefined structure type FILE*/

    fpt = fopen("temperature.dat","r");

    char temp[10];
    float t[7];
    int i, loweringdelta;

    fscanf(fpt, "%s",temp);
    printf("%s",temp);

    loweringdelta = 1;
    for (i=0; i<7; ++i)
    {
        fscanf(fpt, "%f", &t[i]);
        printf("%.2f", t[i]);
        if (i > 0 && (t[i]-t[i-1]<= 0))
        {       
          loweringdelta = t[i]-t[i-1];
        }

    }

    if (loweringdelta > 0)
    {
        // Your error message here
    }

    printf("%f", t[3]);  /*just testing whether the program is reading correctly*/

    fclose(fpt);
    system("pause");
}

Upvotes: 0

ssm
ssm

Reputation: 5383

There is no need to use an extra loop. You can just do

totalInc = 0;

for(i=0;i<7;++i) {
    fscanf(fpt, "%f",&t[i]);
    printf("%.2f",t[i]);

    if (i > 0) {
        if (t[i] > t[i-1]) totalInc += 1;
        else               totalInc -= 1;
    }
}

The totalInc will tell you the number of times the current value is greater than the previous value. For your case, you can then just check for totalInc == 6 but really, you can just check for any number of increments. A positive number will indicate a general incremental trend, while a negative number will indicate a general decreasing trend.

Upvotes: 1

Related Questions