Need some help with ragged array method I was working on I need some help with explaining method

Question

getHighestInColumnIndex

public static int getHighestInColumnIndex(double[][] data,

int col)

Returns index of the largest element of the selected column in the two dimensional array index 0 refers to the first column. If a

row in the two dimensional array doesn't have this column index, it is not an error, it doesn't participate in this method.

Parameters:

data - the two dimensional array

col - the column index to find the largest element of (0 refers to the first column)

Returns:

the index of the largest element of the column

my code

ublic static int getHighestInColumnIndex(double[][] data, int col) {

double max = data[0][col];

int location = -1;

for(int i =0; i<data.length; i++) {

if(col>= 0 && col<data[i].length) 

if(data[i][col]>max) {

location = i;

}

}

return location;

}

Answer 1

You're on the right track, but in the for loop, you have to compare the variable col against the size of data[i].length, or else you are going to compare it against something NULL or undefined, and then it crashes!!!

Here ya go:

class AngieARaggedArrays

{

public static final int MAX_COLUMNS=6;

/*********************************************

Returns the largest column value or -1

************************************************/

public static double getHighestInColumn(double[][]data, int col)

{

double maxVal=-1;

for (int rowLoop=0; rowLoop<data.length; rowLoop++)

{

if (

(col>=0) && (col<data[rowLoop].length)

)

// Then that column EXISTS in this particular row

{

if ( data[rowLoop][col]>maxVal) //the current max value has been DEFEATED!!

{ // new champion ;-)

maxVal = data[rowLoop][col];

}

}

}

return(maxVal);

}

public static void main(String args[])

{

double A[][] = { {5, 4, 3, 2, 1},

{4, 3, 2},

{1, 4, 7, 9, 3, 5},

{7, 8, 4, 1, 2},

{9, 3},

{1, 3, 3, 4, 5},

{2},

{7, 6, 5, 4}

};

AngieARaggedArrays x = new AngieARaggedArrays();

for (int columnLoop=0; columnLoop<x.MAX_COLUMNS; columnLoop++)

{

System.out.println(" The highest value in column " + columnLoop

+ " is : " +x.getHighestInColumn(A,columnLoop));

}

}

}