Is there any way to use hashtables/hashmaps in matlab?

Question

Possible Duplicate: Hash tables in MATLAB General Question Is there any way to get a hashset or hashmap structure in Matlab? I often find myself in situations where I need to find unique entries or check membership in vectors and using commands like `unique()` or logical indexing seems to search through the vectors and is really slow for large sets of values. What is the best way to do this in Matlab? Example Say, for example, that I have a list of primes and want to check if 3 is prime: ``` primes = [2,3,5,7,11,13]; if primes(primes==3) disp('yes!') else disp('no!') end ``` if I do this with long vectors and many times things get really slow. In other languages So basically, is there any equivalents to python's `set()` and `dict()`, or similarly Java's `java.util.HashSet` and `java.util.HashMap`, in Matlab? And if not, is there any good way of doing lookups in large vectors? Edit: reflection on the answers This is the running time i got on the suggestions in the answers. ``` >> b = 1…

Accepted Answer

Like this?

```
>> m = java.util.HashMap;
>> m.put(1,'hello,world');
>> m.get(1)
ans =
hello, world
```

Alternatively, if you want a Matlab-native implementation, try

```
>> m = containers.Map;
>> m('one') = 1;
>> m('one')
ans =
     1
```

This is actually typed - the only keys it will accept are those of type `char`. You can specify the key and value type when you create the map:

```
>> m =  containers.Map('KeyType','int32','ValueType','double');
>> m(1) = 3.14;
>> m(1)
ans =
  3.14
```

You will now get errors if you try to put any key other than an `int32` and any value other than a `double`.

You also have Sets available to you:

```
>> s = java.util.HashSet;
>> s.put(1);
>> s.contains(1)
ans = 
     1
>> s.contains(2)
ans = 
     0
```

Is there any way to use hashtables/hashmaps in matlab?

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