Trying improve this algorithm(Java)

[BrownZeus]

So I have two 2 dimensional arrays that need to be populated from the same initial string array.

 

Given:

String[] input_array//size 54

double[3][9] array1;

double int[3][9] array2;

 

the pattern of input array basically is the first 9 elements map to 1st array in array1, next map to 1st array in array2 and then the pattern repeats.

 

The best I can come up with is:

 

LinkedList<String> inputList = new LinkedList<>(Arrays.asList(input_array);

for(int i = 0; i < array1.length; i++)
{
	for(int j = 0; j < 9; j++)
    {
    	array1[i][j] = Double.parseDouble(inputList.pop());
    }
    for(int j = 0; j < 9; j++)
    {
    	array1[i][j] = Integer.parseInt(inputList.pop());
    }
}

This code works how I want it to, however I don't like that I'm nest two for loops into another for loop.

There has to be a better and cleaner way to do this.

 

Full disclosure this is for work, just trying to improve my algorithm

[manikyath]

as far as i'm aware, a loop in a loop is the way to populate a two-dimensional array.

 

also, you're populating two two-dimensional arrays in 6 lines of code, that's pretty darn clean...

[BobVonBob]

Using LinkedList pop this is the most efficient method to iterate over a 2D array, that's just what the structure of a 2D array requires. Don't optimize before you know you need to.

[BrownZeus]

11 minutes ago, manikyath said:

as far as i'm aware, a loop in a loop is the way to populate a two-dimensional array.

 

also, you're populating two two-dimensional arrays in 6 lines of code, that's pretty darn clean...

 

10 minutes ago, BobVonBob said:

Using LinkedList pop this is the most efficient method to iterate over a 2D array, that's just what the structure of a 2D array requires. Don't optimize before you know you need to.

Getting things right on the first try isn't something I'm used to doing haha. Thank you for the inputs

[WereCatf]

5 hours ago, BrownZeus said:

There has to be a better and cleaner way to do this

You have a bug in your original code: you assigned to array1 in both loops and never used array2 at all.

[WereCatf]

No idea if this is actually any faster than the original code -- probably not -- but it squeezes the code in slightly smaller space:

LinkedList<String> inputList = new LinkedList<>(Arrays.asList(input_array);

for(int i = 0; i < array1.length; i++)
{
	for(int j = 0; j < 9; j++)
    {
    	array1[i][j] = Double.parseDouble(inputList[i * 9 * 2]);
    	array2[i][j] = Integer.parseInt(inputList[i * 9 * 2 + 9]);
    }
}

 

[Lordess]

1 hour ago, doertedev said:

Maybe if you could explain why exactly it is that you're doing what you're doing we can jump in with better approaches. Also give Streams a try.

Obviously it's his homework.

[BrownZeus]

17 hours ago, WereCatf said:

You have a bug in your original code: you assigned to array1 in both loops and never used array2 at all.

You're right, its a typo!

 

15 hours ago, doertedev said:

Maybe if you could explain why exactly it is that you're doing what you're doing we can jump in with better approaches. Also give Streams a try.

Basically I have to take an input of String[], and then the pattern basically is first 9 populate a double array, and then the next 9 populate an int array, and that cycle repeats for a total of 6 arrays total. I did give streams a try, and I have an update! See below!

 

 

14 hours ago, Lordess said:

Obviously it's his homework.

If you look at my OP, i disclaimed right there this is for work, as in my job. If it was homework I wouldn't give rat's behind about algorithm efficiency, or quality. Like most CS majors in the US these days, I got my degree on trash code and caffeine.

 

 

That being said the reason I was doing 2 dimensional arrays was due to a data structure I already had to work with (custom pojos and all), so my solution to get out of using 3 loops was streams!
 

Turned the String[] into a LinkedList and then did this:

 

LinkedList<String> inputList = new LinkedList<>(Arrays.asList(input_array);

for(int i = 0; i < array1.length; i++)
{
	
    	array1[i] = IntStream.range(0, 9).mapToDouble(i -> Double.parseDouble(inputList.pop())).toArray();
    	array2[i] = IntStream.range(0, 9).map(i -> Integer.parseInt(inputList.pop())).toArray();
    
}