无限，而嵌套在MATLAB中的for循环 [英] Infinite while nested in a for loop in matlab

问题描述

我想在循环中嵌套一个循环，在循环中嵌套在Matlab中，以便找到距离数据之间的不同对之间。我的资料有以下形式：

pre code $ ID $ L $ $ $ $ 1 $ 33.56 40.89 803
2 32.45 41.03 803
3 35.78 39.85 803
2 33.04 40.21 804
3 36.89 40.23 804
2 33.98 39.33 806
2 33.67 39.73 809
3 37.02 40.77 809


lon 和 lat 是地理坐标。在 for 循环中，我想从矩阵中取第一行，然后在中，而循环检查所有其他只要中的条件是 true ，就可以计算行和行之间的距离。我的意思是，对于第一行，我希望程序计算在时间803处的对1-2,1-3之间的距离，然后再次在时间803处的距离1-2,1-3。当我将循环的中的步增加1时，程序应该计算803的2-3对和804的2-3等等。为此，我已经为循环写了如下：



 对于ii = 1：长度（MM（：，4））
t = MM（ii，4）; 
 ind1 = ii; 
长度（ind1）; 
 lat1 = lat（ind1）; 
 lon1 = lon（ind1）; 
 jj = ii +1; （MM（：，4））
 ind2 = jj（t <=（MM（ii，4）+5））
， ; 
长度（ind2）; 
 lat2 = lat（ind2）; 
 lon2 = lon（ind2）; 
 w = MM（jj，4）; 
 end 
 
 dis =距离（lat1，lon1，lat2，lon2）; 
 t = t + 1; 
 end 
 
 
如果dis <= 1 
 
 [contact] = [ind1，ind2，t，w]; 
 end 
 
 end 
  

使用 for 循环我得到一个无限的而循环。我的问题是为什么我得到这个无限的而循环，我应该怎么做，因为我所描述的？

解决方案

我终于找到了答案。

  for ii = 1：length（MM（：，4））
t = MM（ii，4）; 
 ind1 = ii; 
长度（ind1）; 
 lat1 = lat（ind1）; 
 lon1 = lon（ind1）; 
 jj = ii + 1; （MM（jj，4）-t≤5）
 
 ind2 = jj; 
 
， 
长度（ind2）; 
 lat2 = lat（ind2）; 
 lon2 = lon（ind2）; 
 dis = distance（lat1，lon1，lat2，lon2）; 
 
如果dis <= 1 
 contact = [MM（ind1,1），MM（ind2,1），t，MM（jj，4）] 
 
 else 
 fprintf（'没有距离小于1km \\\
'）
 end 
 
 jj = jj + 1; 
 end 
 
 end 
  

嵌套 for 循环在中，而是错误的，根本没有任何用处。第二个问题是中的条件，而。我之前在中作了比较，而条件是反写的，没有任何意义。第三个问题是 if if 语句。通过在循环中加入 if 语句，而循环中的结果是在联系人中。


I want to make a while loop, nested in a for loop in Matlab in order to find the distance between different pairs in the data. My data have the following form

    ID  lon     lat     time
    1   33.56   40.89   803
    2   32.45   41.03   803
    3   35.78   39.85   803
    2   33.04   40.21   804
    3   36.89   40.23   804
    2   33.98   39.33   806
    2   33.67   39.73   809
    3   37.02   40.77   809

lon and lat are geographical coordinates. In the for loop, I want to take the first row from the matrix and then in the while loop check all other rows and compute the distance between the pairs as long as the condition in the while is true. What I mean is that for the first row I want the program to compute the distance between the pairs 1-2, 1-3 at time 803, then the distance 1-2, 1-3 at time 803 again. When I increment the step in the for loop by 1, again, the program should compute the distance between the pairs 2-3 at 803, then 2-3 at 804 and so on, so forth. To do that, I've written the for loop as below:

for ii = 1:length(MM(:,4))
    t = MM(ii,4);
    ind1 = ii;
    length(ind1);
    lat1 = lat(ind1);
    lon1 = lon(ind1);
    jj = ii +1;

    while (t <= (MM(ii,4)+5))
        for jj = 2:length(MM(:,4))
            ind2 = jj;
            length(ind2);
            lat2 = lat(ind2);
            lon2 = lon(ind2);
            w = MM(jj,4);
        end

        dis = distance(lat1, lon1, lat2, lon2);
        t = t + 1;
    end


    if dis <= 1

        [contact] = [ind1, ind2, t, w];
    end

end

With this for loop I get an infinite while loop. My question is why do I get this infinite while loop and how am I supposed to make it work as I described?

解决方案

I finally found the answer. I post it here for future use.

for ii = 1:length(MM(:,4))
    t = MM(ii,4);
    ind1 = ii;
    length(ind1);
    lat1 = lat(ind1);
    lon1 = lon(ind1);
    jj = ii + 1;

    while (MM(jj,4) - t <= 5)

            ind2 = jj;
            length(ind2);
            lat2 = lat(ind2);
            lon2 = lon(ind2);
            dis = distance(lat1, lon1, lat2, lon2);

            if dis <= 1
                contact = [MM(ind1,1), MM(ind2,1), t, MM(jj,4)]   

            else
                fprintf('There is no distance smaller than 1km\n')
            end

            jj = jj + 1;
    end

end

As it seems the nested for loop in the while was wrong and without any use at all. The second problem was the condition in the while. The comparison, I previously made in the while condition was written backwards and had no meaning. And the third problem was the if statement. By putting the if statement in the while loop, I had the result in the contact.

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