Python Sets - Using Operators on Sets
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In addition to the normal mathematical operators you can use with Sets, the following are also useful:
Union
If you wish to merge two Sets, you can do so with the Union operation:
usr/local/bin/python
firstset = Set([1, 2, 3])
secondset = Set([1, 4, 5, 6])
firstset.union(secondset)
print firstset
This will create a union between the two Sets and print the following (remember: it will not store duplicate data):
1 2 3 4 5 6
Intersection
If you want to find out if two Sets have any data that are the same, you can use the Intersection operation. Behold!
usr/local/bin/python
firstset = Set([1, 2, 3])
secondset = Set([1, 4, 5, 6])
firsttest.intersection(secondset)
This will return any data that is the same in both Sets. The result here would be:
1
This is because both sets have an element with the value 1 in it.
Symmetric Difference
If you want to print the values in two Sets that are not the same, you can use the Symmetric Difference function.
usr/local/bin/python
firstset = Set([1, 2, 3])
secondset = Set([1, 4, 5, 6])
firstset.symmetric_difference(secondset)
This would result in the values 2, 3, 4, 5, 6. It will not show 1, because one is in both Sets.
Set Difference
If you want to find what values are in firstset that are not in secondset, you can use the Set Difference operation. I know you are dying to see it, so here it is:
usr/local/bin/python
firstset = Set([1, 2, 3])
secondset = Set([1, 4, 5, 6])
firstset.difference(secondset)
This results in the values 2 and 3. This is because the values 2 and 3 are not in the secondset Set, whereas the number 1 is.
So we did not get to discuss Operators in this article; however, we will definitely discuss them in our next episode, as they will be the focus. In the meantime, here is that Operator Table again, just to refresh your memory:
Symbol | Type | What it Does |
+ | Mathematical | Addition |
- | Mathematical | Subtraction |
* | Mathematical | Multiplication |
/ | Mathematical | Division |
// | Mathematical | Truncating Division |
** | Mathematical | Powers |
% | Modulos | Returns the remainder from a division |
<< | Shift | Left Shift |
>> | Shift | Right Shift |
& | Logical | And |
| | Logical | Or |
^ | Logical | Bitwise XOR |
~ | Logical | Bitwise Negation |
< | Comparison | Less than |
> | Comparison | Greater than |
'==' | Comparison | Equal to |
!= | Comparison | Not Equal To |
>= | Comparison | Greater than or Equal To |
<= | Comparison | Less than or Equal To |
'=' | Assignment | Assigns a value |
+= | Assignment | Adds and assigns a value |
-= | Assignment | Subtracts and Assigns a value |
*= | Assignment | Multiplies and assigns a value |
/= | Assignment | Divides and assigns a value |
//= | Assignment | Truncate Divides and assigns a value |
**= | Assignment | Powers and assigns |
%= | Assignment | Modulus and assigns |
>> | Assignment | Shifts and assigns |
<< | Assignment | Shifts and assigns |
And | Boolean |
|
Or | Boolean |
|
Not | Boolean |
|
Till then...
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