Convert an object of object arrays into several double arrays in C#

Question

The problem is extracting double arrays in a multidimensional object array which itself is kept in a one-dimensional object array that is contained in a variable of object type.

I am trying to use Matlab API in a C# program. The Matlab script returns values in Matlab's matrix form which is then returned to the C# program as an object variable described as above.

An example of the returned data is as follows. The returned variable is called result which contains a one-dimensional object array. The one-dimensional object array contains a 1x4 object array and each of the objects in the 1x4 array contains a double array.

-       result  {object[1]}
  -     [0] {object[1, 4]}
    +       [0, 0]  {double[500, 6]}
    +       [0, 1]  {double[500, 6]}
    +       [0, 2]  {double[500, 6]}
    +       [0, 3]  {double[500, 6]}

How do I extract these double arrays?

Update

To get you a clearer picture of the variable in question, you can run the following code.

object result;
var resultSub1 = new object[1];

double[,] data1 = {{0,0},{0,0}};
double[,] data2 = {{0,0},{0,0}};
double[,] data3 = {{0,0},{0,0}};
double[,] data4 = {{0,0},{0,0}};
object[,] resultSub2 = { { data1, data2, data3, data4 } };

resultSub1[0] = resultSub2;
result = resultSub1;

How do I extract data1, data2, data3 and data4?

Please be more specific. You show a result value that looks like it's a one-dimensional, single-element array containing a two-dimensional array, with length of the first rank of just 1, a length of the second rank of 4. But even if one assumes that's what you mean, it's not clear at all what it is you want to convert that to. — Peter Duniho
– Peter Duniho, Commented Dec 23, 2014 at 18:04
Sorry about my English. @PeterDuniho your assumption is correct. The result is a single-element array containing a two-dimensional array which further contains four two-dimensional arrays. I would like to get those four double[500,6] and store them separately in four new double arrays. The trouble is I define the result as an object rather than an array, but the mLab.Feval method returns an array[object]. I couldn't even get the object[1] out of result{object[1]}. — Anthony
– Anthony, Commented Jan 7, 2015 at 15:04
So for example: object result_parent; object[] result_sub1 = new object[1]; double[,] data1 = {{0,0},{0,0}}; double[,] data2 = {{0,0},{0,0}}; double[,] data3 = {{0,0},{0,0}}; double[,] data4 = {{0,0},{0,0}}; object[,] result_sub2 = { { data1, data2, data3, data4 } }; result_sub1[0] = result_sub2; result_parent = result_sub1; How do I call data1, data2, data3 and data4? — Anthony
– Anthony, Commented Jan 7, 2015 at 15:10

Peter Duniho · Accepted Answer · 2015-01-07 16:50:00Z

1

Based on your clarification, I believe this is the code you're looking for:

double[,] data1, data2, data3, data4;

object[] resultArray = (object[]) result;
object[,] dataArrays = (object[,]) resultArray[0];

data1 = (double[,]) dataArrays[0, 0];
data2 = (double[,]) dataArrays[0, 1];
data3 = (double[,]) dataArrays[0, 2];
data4 = (double[,]) dataArrays[0, 3];

It's just a matter of casting appropriately at each level of the data structure. First, cast to the single-dimensional, single-element array type that the result value actually is. Then, retrieve that array's single element, casting it to the two-dimensional, four-element array type that it actually is. Finally, retrieve each of the four elements, casting each to the two-dimensional array of double values that it actually is.

answered Jan 7, 2015 at 16:50

Peter Duniho

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1 Comment

Anthony Over a year ago

This is brilliant! Your solution is simple yet works very well. Thank you @Peter for your solution and explanation.

Jason Faulkner · Accepted Answer · 2014-12-23 17:54:40Z

0

Is there a way to get those double arrays inside this object result.

var subArrays = result[0];

The above would create subArrays which has 4 indexes (the double arrays).

If you wanted to combine all the double arrays into a single array (i.e. combine the 4 separate arrays) then this should work:

var allValues = new List<double[][]>();
foreach var subArray in subArrays
{
    allValues.AddRange(subArray);
}
var allValuesArray = allValues.ToArray();

answered Dec 23, 2014 at 17:54

Jason Faulkner

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2 Comments

Anthony Over a year ago

Thanks Jason. It's not possible to call result[0], because the variable result was defined as object result. Sorry I just realised that I didn't explain my questions clearly. Please see the edits I made to the main post. Thanks!

Jason Faulkner Over a year ago

@Anthony - In light of this, my answer really isn't applicable. I will delete it shortly.

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