C# 计算量大，如何让它更快
我知道这是一个愚蠢的问题，为什么这个代码 minX 的计算成本很高，但我想，有人可能会告诉我我的错误。谢谢
// getMap is a 2 dimentional array of type short I need to find maxX,minX,maxY,minY
//Can't use Math.Min , as it will get the lower bound i.e 0, i want values after filtering
for (int X = 0; X < getMap.GetLength(0); X++)
{
for (int Y = 0; Y < getMap.GetLength(1); Y++)
{
if((short)getMap.GetValue(X,Y) != 0)
{
//if i take it out, it works fine ,I need to
if (minX > X )
minX = X;
else
X = minX;
// Prints some stuff and does other computation
}
}
}
// Draws image
I know its a dumb question to ask about , why this code minX is computationally expensive, but i thought, someone might inform me of my mistake. Thanks
// getMap is a 2 dimentional array of type short I need to find maxX,minX,maxY,minY
//Can't use Math.Min , as it will get the lower bound i.e 0, i want values after filtering
for (int X = 0; X < getMap.GetLength(0); X++)
{
for (int Y = 0; Y < getMap.GetLength(1); Y++)
{
if((short)getMap.GetValue(X,Y) != 0)
{
//if i take it out, it works fine ,I need to
if (minX > X )
minX = X;
else
X = minX;
// Prints some stuff and does other computation
}
}
}
// Draws image
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评论（2）
else X = minX;部分没有多大意义。它可能会导致无限循环，因为您将循环变量X设置为较低的值。仅当最多 1 列包含非零值时，您的代码才会终止（假设您将 minX 初始化为一个大值）。
例如，假设
X=0和X=1列在某处都包含非零值。然后，当它达到 0 列中的非零值时，minX设置为 0。然后，它通过X=1达到非零值，注意到minX> ;X为 false，并将 X 设置回 0。并永远重复。the
else X = minX;part doesn't make much sense. It can cause an endless loop because you're setting back the loop variableXto a lower value.Your code will only terminate if at most 1 column contains a non zero value(assuming you initialized minX to a large value).
For example assume that both the
X=0and theX=1column contain a non zero value somewhere. Then when it hits the non zero value in the 0 columnminXis set to 0. Then later it hits the non zero value withX=1notices thatminX>Xis false and sets X back to 0. And repeat forever.我不知道
(short)getMap.GetValue(X,Y)与getmap[X,Y]相比如何，但似乎过于复杂。您可以做的是将
short[,] getMap替换为short[][] getMap。在这些嵌套循环场景中，数组的数组（锯齿状数组）通常更快，因为抖动可以更好地优化范围检查。
I don't know how
(short)getMap.GetValue(X,Y)compares to justgetmap[X,Y]but is seems over-complicated.What you can do is to replace
short[,] getMapwithshort[][] getMap.Array-of-array (jagged arrays) are ususally faster in these nested loop scenarios because the Jitter can optimize range checking better.