如何研究一个点的邻域？

时间：2017-05-11 11:47:58

标签： matlab

下午好，

如何研究矩阵的点P（x，y）的邻域？例如在配置8连接中我的点P（x，y）有8个邻居，我想提取具有最小值并获得其坐标的那个

例如：     05-01 14:03:13.824 1267-1267/? E/Hyphenator: error loading hyphenation /system/usr/hyphen-data/hyph-as.hyb java.io.FileNotFoundException: /system/usr/hyphen-data/hyph-as.hyb: open failed: ENOENT (No such file or directory) at libcore.io.IoBridge.open(IoBridge.java:455) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247) at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118) at android.text.Hyphenator.init(Hyphenator.java:224) at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252) at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722) Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory) at libcore.io.Posix.open(Native Method) at libcore.io.BlockGuardOs.open(BlockGuardOs.java:187) at libcore.io.IoBridge.open(IoBridge.java:441) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247)  at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118)  at android.text.Hyphenator.init(Hyphenator.java:224)  at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252)  at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722)  05-01 14:03:13.824 1267-1267/? E/Hyphenator: error loading hyphenation /system/usr/hyphen-data/hyph-bn.hyb java.io.FileNotFoundException: /system/usr/hyphen-data/hyph-bn.hyb: open failed: ENOENT (No such file or directory) at libcore.io.IoBridge.open(IoBridge.java:455) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247) at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118) at android.text.Hyphenator.init(Hyphenator.java:224) at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252) at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722) Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory) at libcore.io.Posix.open(Native Method) at libcore.io.BlockGuardOs.open(BlockGuardOs.java:187) at libcore.io.IoBridge.open(IoBridge.java:441) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247)  at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118)  at android.text.Hyphenator.init(Hyphenator.java:224)  at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252)  at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722)  05-01 14:03:13.824 1267-1267/? E/Hyphenator: error loading hyphenation /system/usr/hyphen-data/hyph-cy.hyb java.io.FileNotFoundException: /system/usr/hyphen-data/hyph-cy.hyb: open failed: ENOENT (No such file or directory) at libcore.io.IoBridge.open(IoBridge.java:455) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247) at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118) at android.text.Hyphenator.init(Hyphenator.java:224) at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252) at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722) Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory) at libcore.io.Posix.open(Native Method) at libcore.io.BlockGuardOs.open(BlockGuardOs.java:187) at libcore.io.IoBridge.open(IoBridge.java:441) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247)  at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118)  at android.text.Hyphenator.init(Hyphenator.java:224)  at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252)  at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722)  05-01 14:03:13.825 1267-1267/? E/Hyphenator: error loading hyphenation /system/usr/hyphen-data/hyph-da.hyb java.io.FileNotFoundException: /system/usr/hyphen-data/hyph-da.hyb: open failed: ENOENT (No such file or directory) at libcore.io.IoBridge.open(IoBridge.java:455) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247) at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118) at android.text.Hyphenator.init(Hyphenator.java:224) at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252) at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722) Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory) at libcore.io.Posix.open(Native Method) at libcore.io.BlockGuardOs.open(BlockGuardOs.java:187) at libcore.io.IoBridge.open(IoBridge.java:441) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247)  at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118)  at android.text.Hyphenator.init(Hyphenator.java:224)  at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252)  at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722)  05-01 14:03:13.825 1267-1267/? E/Hyphenator: error loading hyphenation /system/usr/hyphen-data/hyph-de-1901.hyb java.io.FileNotFoundException: /system/usr/hyphen-data/hyph-de-1901.hyb: open failed: ENOENT (No such file or directory) at libcore.io.IoBridge.open(IoBridge.java:455) at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247) at android.text.Hyphenator.loadHyphenator(Hyphenator.java:118) at android.text.Hyphenator.init(Hyphenator.java:224) at com.android.internal.os.ZygoteInit.preloadTextResources(ZygoteInit.java:252) at com.android.internal.os.ZygoteInit.preload(ZygoteInit.java:206) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:722) 我希望研究r=rand(5)

的邻居

2 个答案:

答案 0 :(得分：1)

如果我理解正确，您只需要做

sub=P(x-1:x+1,y-1:y+1)
[v i]=min(sub(:))

然后v是最小值，i是矢量化子矩阵中的索引。根据{{​​1}}和x的值查找原始索引是微不足道的（请记住，matlab是列专业）。

答案 1 :(得分：1)

你知道在这种情况下，邻居将位于[x，y] + [-1，-1]，[ - 1,0] ...... [1,1]。暂时忽略两件事 - 这些点可能落在矩阵之外，并且该中心包含在其中。当你忽略这些2时，最终会得到

neighbors = r(x-1:x+1, y-1:y+1); % 3x3 matrix.

找到最低限度及其位置是微不足道的。

现在，重新考虑这两个遗漏：
首先你应该用nan填充矩阵来处理index out of range问题（或者根本不看边缘点，你通常最终会遇到比他们的价值更多的麻烦）。
然后，要排除中心，你应该制作一个面具：

mask = [true, true, true; true, false, true; true, true, true];

最后，找到最小邻居可能很简单：

[minValue] = min(neighbors(mask));

这对于找到最小值确实很好，但是找到最小位置几乎没用。嗯，这里很简单，因为这个掩模，第5点未命中，通常掩模可能是一些较大的圆形（如果你不仅考虑直接邻居而是说距离<3的所有点），那就变得很痛苦将此线性索引映射回原始点。

一个简单的解决方法是

neighbors(~mask) = nan; % set values you don't want to nan.
[minValue, minPosLinear] = min(neighbors(:))

此时，只需重塑minPosLinear以协调并添加中心的坐标。

此过程很容易扩展到搜索任何其他形状的点 - 只需填充足够大的填充（或在边缘上排除足够大的点带），使足够大的初始矩形窗口加上合适的蒙版。

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