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假设我在 Java 中有一个像这样的二维数组(矩阵)......

int[][] MyMat = {{0,1,2,3,4}, {9,8,7,6,5}};

如果我想提取列,我可以像这样轻松地做到这一点......

int[] My0= MyMat[0]; //My0 = {0,1,2,3,4}
int[] My1= MyMat[1]; //My1 = {9,8,7,6,5}

但是如何提取行?...

int[] My_0= ?; //My_0 = {0,9}
int[] My_1= ?; //My_1 = {1,8}
int[] My_2= ?; //My_2 = {2,7}
int[] My_3= ?; //My_3 = {3,6}
int[] My_4= ?; //My_4 = {4,5}

有没有实现这一目标的捷径?

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3 回答 3

4

如果要获取行,则需要从每个数组中获取值,然后根据这些值创建一个新数组。您可以手动分配值,或使用 for 循环,例如 ...

int[][] MyMat = {{0,1,2,3,4}, {9,8,7,6,5}};

// get your columns... (easy)
int[] My0= MyMat[0]; //My0 = {0,1,2,3,4}
int[] My1= MyMat[1]; //My1 = {9,8,7,6,5}

// get the rows... (manually)
int[] My_0= new int[]{MyMat[0][0],MyMat[1][0]}; //My_0 = {0,9}
int[] My_1= new int[]{MyMat[0][1],MyMat[1][1]}; //My_1 = {1,8}
int[] My_2= new int[]{MyMat[0][2],MyMat[1][2]}; //My_2 = {2,7}
int[] My_3= new int[]{MyMat[0][3],MyMat[1][3]}; //My_3 = {3,6}
int[] My_4= new int[]{MyMat[0][4],MyMat[1][4]}; //My_4 = {4,5}

// get the rows... (as a for-loop)
int size = MyMat.length;
int[] My_0 = new int[size]; //My_0 = {0,9}
int[] My_1 = new int[size]; //My_1 = {1,8}
int[] My_2 = new int[size]; //My_2 = {2,7}
int[] My_3 = new int[size]; //My_3 = {3,6}
int[] My_4 = new int[size]; //My_4 = {4,5}
for (int i=0;i<size;i++){
    My_0[i] = MyMat[i][0];
    My_1[i] = MyMat[i][1];
    My_2[i] = MyMat[i][2];
    My_3[i] = MyMat[i][3];
    My_4[i] = MyMat[i][4];
}

否则,请转动整个数组,以便它存储{row,column}而不是{column,row},像这样......

int[][] MyMat = {{0,9},{1,8},{2,7},{3,6},{4,5}};

// get the rows... (easy)
int[] My_0= MyMat[0]; //My_0 = {0,9}
int[] My_1= MyMat[1]; //My_1 = {1,8}
int[] My_2= MyMat[2]; //My_2 = {2,7}
int[] My_3= MyMat[3]; //My_3 = {3,6}
int[] My_4= MyMat[4]; //My_4 = {4,5}

// get the columns... (manually)
int[] My0= new int[]{MyMat[0][0],MyMat[1][0],MyMat[2][0],MyMat[3][0],MyMat[4][0]}; //My0 = {0,1,2,3,4}
int[] My1= new int[]{MyMat[0][1],MyMat[1][1],MyMat[2][1],MyMat[3][1],MyMat[4][1]}; //My1 = {9,8,7,6,5}

// get the columns... (as a for-loop)
int size = MyMat.length;
int[] My0 = new int[size]; //My0 = {0,1,2,3,4}
int[] My1 = new int[size]; //My1 = {9,8,7,6,5}
for (int i=0;i<size;i++){
    My0[i] = MyMat[0][i];
    My1[i] = MyMat[1][i];
}

请注意,不可能有一种速记方式可以让您轻松获取行和列 - 您必须决定您想要更多,并将数组构造为该格式。

于 2012-06-18T02:35:05.187 回答
1

如果我们知道二维数组的大小行和列大小,我们可以实现如下

让 No.of Rows - 行

让列数 -clmns

int[][] my = new int[clmns][rows];
for(int i=0;i<clmns;i++)
for(int j=0;j< rows; j++)
 my[i][j]=MyMat[j][i]; 

然后每次取一列给你原始数组的行数组。

否则,如果在程序运行时给出了行数,则可以使用 ArrayList 数组和行数。

于 2012-06-20T09:40:28.267 回答
0

它很简单:

1. 转置您的二维矩阵 2 。然后按照你的意思做[] My0= MyMat[0]; int[] My1= MyMat[1];

于 2015-04-08T23:18:55.230 回答