Alivajorg - 5 months ago 7

Android Question

I need to do the chiSquaredTest. I'm using the Apache Commons Math library but not sure what is a

`long[][]`

`long[]`

`public double chiSquareTest(long[][] counts)`

throws NullArgumentException,

DimensionMismatchException,

NotPositiveException,

MaxCountExceededException

Returns the observed significance level, or p-value, associated with a chi-square test of independence based on the input counts array, viewed as a two-way table.

The rows of the 2-way table are count[ 0 ], ... , count[count.length - 1]

Preconditions:

- List item All counts must be ≥ 0.
- The count array must be rectangular (i.e. all count[ i ] subarrays must have the same length).
- The 2-way table represented by counts must have at least 2 columns and at least 2 rows.
- If any of the preconditions are not met, an IllegalArgumentException is thrown.

Parameters:

- counts - array representation of 2-way table

Returns:

- p-value

Answer

`long[]`

- it is one dimensional array.

```
long[] array = new long[4];
/* result of that array
{0, 0, 0, 0}
*/
```

`long[][]`

- it is array of arrays / two dimensional array.

```
long[][] array2 = new long[4][];
array2[0] = new long[1];
array2[1] = new long[2];
array2[2] = new long[4];
array2[3] = new long[3];
/* result of that array
{
{0},
{0, 0},
{0, 0, 0, 0},
{0, 0, 0},
}
*/
```

or it can be like that:

```
long[][] array = new long[4][4];
/* result of that array
{
{0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0},
}
*/
```

For more examples go to this link.

Source (Stackoverflow)

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