Dividing an array of numbers with another array of numbers in Processing

Question

I am a beginner to coding and trying to make simple data visualizations using processing. In order to test, i created a csv file where three columns of data are listed where the 2nd and third are numbers. I parsed the columns and tried dividing the 2nd column of numbers with the 3rd. But unfortunately the results are showing zero.

the code is



String tag = "dataset.csv";
String [] rawData;

int [] marks = new int[6];
int [] maxMarks = new int[6];

float [] percentage = new float[6];

void setup() {
  size(800, 800);
  smooth();

  rawData = loadStrings(tag);

  for (int i = 1; i<rawData.length; i++) {
    String [] thisRow = split(rawData[i], ",");

    String subject = thisRow[0];       //// name of the subject
    marks[i-1] = int(thisRow[1]);       //// marks recieved
    maxMarks [i-1] = int(thisRow[2]);         //// maximum marks
    percentage [i-1]    = (marks[i-1]/maxMarks[i-1]);
  }
  println(marks);       //// prints the numbers 80,45,40,25,30,40
  println(maxMarks);    //// prints the numbers 100,50,50,50,50,50
  println(percentage);  //// prints 0.0,0.0,0.0,0.0,0.0,0.0,
}

void draw() {
}

I wanted the percentage to be calculated and displayed. :(

It would be a great help if someone can help me to sort this out. Many thanks in advance!

Cheers, Yousuf

you are getting 0 as result. there are many situations where this can occur.what is the data type of marks[i-1] and maxMarks[i-1]. is it going out of data type range? check out the possible cases. — Ritt
– Ritt, Commented Oct 12, 2015 at 10:01

fishshrimp鱼虾爆栈 · Accepted Answer · 2015-10-12 10:19:42Z

1

Are you using c++ ?

haha , you need to know , an integer divide integer , the result must be an integer !

you want to get a percent , that is a float value .

so just cast it !

static_cast<float>(int_value ) [ C++ style ]

or

float(int_value) [c style] is both ok ~

so , just change here :

percentage [i-1]    = (marks[i-1]/maxMarks[i-1]);

to

percentage [i-1]    = (float(marks[i-1])/maxMarks[i-1]) * 100 ;

or

percentage [i-1]    = (static_cast<float>(marks[i-1])/maxMarks[i-1]) * 100;

*100 , because you want a percent value

edited Oct 12, 2015 at 10:19

answered Oct 12, 2015 at 10:13

fishshrimp鱼虾爆栈

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1 Comment

yousufali.n Over a year ago

Thank you so much 小文件! Such a simple one :) I am using Processing which works based on Java. I just turned the integers into float, and now it works

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