如何使用Cgo访问MATLAB数组中的值？

huangapple
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英文:

How do I access the values inside a MATLAB array using Cgo?

问题

使用MatLab C API和Go的Cgo包，我正在尝试在我的Go程序中读取一个24x3000000的矩阵内的mat文件。我能够成功读取矩阵的维度，但是如何访问每个单元格内的值呢？（最终目标是将该矩阵作为切片返回给我的Go程序。）

  1. var realDataPtr *C.double
  2. var field *C.mxArray
  4. fieldName := C.CString("data")
  5. field = C.mxGetField(pa, 0, fieldName)
  7. rowTotal := C.mxGetM(field) // 输出为24
  8. colTotal := C.mxGetN(field) // 输出为3000000
  10. // 获取矩阵中数据的指针
  11. realDataPtr = C.mxGetPr(field)
  13. // 打印矩阵中的每个元素
  14. for row := 0; row < int(rowTotal); row++ {
  15.     for col := 0; col < int(colTotal); col++ {
  16.         // 这是我卡住的地方
  17.     }
  18. }

参考资料：这里是C语言的矩阵库API。

英文:

Using the MatLab C API and Go's Cgo package, I'm attempting to read a 24x3000000 matrix inside a mat-file in my Go program. I'm able to successfully read the dimensions of the matrix but how do I access the values inside each cell? (The goal is ultimately to return this matrix as a slice to my Go program.)

  1. var realDataPtr *C.double
  2. var field *C.mxArray
  4. fieldName := C.CString(&quot;data&quot;)
  5. field = C.mxGetField(pa, 0, fieldName)
  7. rowTotal := C.mxGetM(field) // outputs 24
  8. colTotal := C.mxGetN(field) // outputs 3000000
  10. // get pointer to data in matrix
  11. realDataPtr = C.mxGetPr(field)
  13. // Print every element in the matrix
  14. for row := 0; row &lt; int(rowTotal); row++ {
  15. 	for col := 0; col &lt; int(colTotal); col++ {
  16. 	    // This is where I get stuck
  17. 	}
  18. }

For reference, here's the Matrix Library API for C

答案1

得分: 1

MATLAB中的矩阵数据以列优先顺序存储，这意味着数据的列按顺序存储在内存中（与C和类似的语言相反）。因此，如果你想在C中按顺序访问数据（很遗憾，我对Go语法不太熟悉），你可以这样做：

  1. for(col=0;col<colTotal;++col)
  2. {
  3.     for(row=0;row<rowTotal;++row)
  4.     {
  5.         data = realDataPtr[col*rowTotal + row];
  6.     }
  7. }
英文:

Matrix data in MATLAB are stored in column major order, which means that the columns of the data are stored in sequential order in memory (this is the opposite to C and similar languages). Thus, if you wanted to access the data sequentially in C (I'm not immediately familiar with Go syntax, unfortunately), you could do the following:

  1. for(col=0;col&lt;colTotal;++col)
  2. {
  3.     for(row=0;row&lt;rowTotal;++row)
  4.     {
  5.         data = realDataPtr[col*rowTotal + row];
  6.     }
  7. }

答案2

得分: 1

未经测试，因为我没有MatLab。例如，

  1. import (
  2.     "fmt"
  3.     "unsafe"
  4. )
  6. // 打印矩阵中的每个元素
  7. ptr := uintptr(unsafe.Pointer(realDataPtr))
  8. for col := 0; col < int(colTotal); col++ {
  9.     for row := 0; row < int(rowTotal); row++ {
  10.         // 这是我卡住的地方
  11.         elem := *(*float64)(unsafe.Pointer(ptr))
  12.         fmt.Println(elem)
  13.         ptr += 8
  14.     }
  15. }
英文:

Untested, since I don't have MatLab. For example,

  1. import (
  2. 	&quot;fmt&quot;
  3. 	&quot;unsafe&quot;
  4. )
  6. // Print every element in the matrix
  7. ptr := uintptr(unsafe.Pointer(realDataPtr))
  8. for col := 0; col &lt; int(colTotal); col++ {
  9. 	for row := 0; row &lt; int(rowTotal); row++ {
  10. 		// This is where I get stuck
  11. 		elem := *(*float64)(unsafe.Pointer(ptr))
  12. 		fmt.Println(elem)
  13. 		ptr += 8
  14. 	}
  15. }

huangapple
  • 本文由 发表于 2014年11月2日 09:37:32
  • 转载请务必保留本文链接：https://go.coder-hub.com/26695158.html
  • c
  • cgo
  • go
  • mat-file
  • matlab
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