MATLAB:SQL风格的联接操作 [英] MATLAB: SQL-style join operation

问题描述

我想用Matlab做一个SQL风格的联接.我可以通过创建数据集(统计工具箱)，进行联接，转换回并再次删除数据集来做到这一点:

I would like to do an SQL-style join with Matlab. I could do it by creating datasets (stats toolbox), doing the join, converting back and deleting the datasets again:

A1 = [10 10 20 20 30 30 50 50]';
B1 = (10:10:70)';
B2 = (1:7)';

dsA = dataset({A1, 'Key'});
dsB = dataset({B1, 'Key'}, {B2, 'Idx'});
dsA = join(dsA, dsB, 'key', 'Key');

结果:

Key    Idx
10     1  
10     1  
20     2  
20     2  
30     3  
30     3  
50     5  
50     5  

我的问题:是否还有另一种方法，不使用数据集并且不使用for循环?

My Question: Is there another way of doing this, without using datasets and without for loops?

非常感谢您的帮助！

推荐答案

在您的示例中，您只需使用 ISMEMBER :

For your example, you could simply use ISMEMBER:

[~,loc] = ismember(A1,B1);
dsA = [B1(loc) B2(loc)]

结果:

dsA =
    10     1
    10     1
    20     2
    20     2
    30     3
    30     3
    50     5
    50     5

注意:这假定A1中的所有元素都在B1中找到.如果不是总是这样，则可以使用ISMEMBER的第一个输出来过滤loc ...

Note: this assumes that all the elements in A1 are found in B1. If that not always the case, you could use the first output of ISMEMBER to filter the zero-values in loc...

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