# Apply operations on a collection in Julia – map() and map!() Methods

The `map()` is an inbuilt function in julia which is used to transform the specified collection by using specified operation to each element.
Syntax: map(f, c…) Parameters:
• f: Specified operation.
• c: Specified collection.
Returns: It returns the transformed elements.
Example:
 `# Julia program to illustrate  ``# the use of map() method `` ` `# Getting the transformed elements. ``println(``map``(x ``-``> x ``*` `2``, [``5``, ``10``, ``15``])) ``println(``map``(``+``, [``1``, ``2``, ``3``], [``10``, ``20``, ``30``])) ``println(``map``(x ``-``> x ``/` `5``, [``5``, ``10``, ``15``])) ``println(``map``(``-``, [``10``, ``20``, ``30``], [``1``, ``2``, ``3``])) `

Output:
```[10, 20, 30]
[11, 22, 33]
[1.0, 2.0, 3.0]
[9, 18, 27]```

#### map!()

The `map!()` is an inbuilt function in julia. This function is same as map() function but stores the result in destination rather than a new collection. The destination must be at least as large as the first collection.
Syntax: map!(function, destination, collection…) Parameters:
• function: Specified operation.
• destination: The destination where the result get stored.
• collection: Specified collection.
Returns: It returns the transformed elements.
Example:
 `# Julia program to illustrate  ``# the use of map !() method `` ` `# Getting the transformed elements. ``a ``=` `zeros(``3``); ``map` `!(x ``-``> x ``*` `3``, a, [``1``, ``2``, ``3``]); ``println(a) `` ` `b ``=` `ones(``3``); ``map` `!(x ``-``> x ``/` `3``, b, [``3``, ``6``, ``9``]); ``println(b) `

Output:
```[3.0, 6.0, 9.0]
[1.0, 2.0, 3.0]
```

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