﻿ Python: Generate all the combinations with repetitions of k types of things taken n at a time - w3resource

# Python: Generate all the combinations with repetitions of k types of things taken n at a time

## Python Itertools: Exercise-13 with Solution

Write a Python program that will select a specified number of colours from three different colours, and then generate all the combinations with repetitions.

Sample Solution:

Python Code:

``````from itertools import combinations_with_replacement

def combinations_colors(l, n):
return combinations_with_replacement(l,n)
l = ["Red","Green","Blue"]
print("Original List: ",l)
n=1
print("\nn = 1")
print(list(combinations_colors(l, n)))
n=2
print("\nn = 2")
print(list(combinations_colors(l, n)))
n=3
print("\nn = 3")
print(list(combinations_colors(l, n)))
```
```

Sample Output:

```Original List:  ['Red', 'Green', 'Blue']

n = 1
[('Red',), ('Green',), ('Blue',)]

n = 2
[('Red', 'Red'), ('Red', 'Green'), ('Red', 'Blue'), ('Green', 'Green'), ('Green', 'Blue'), ('Blue', 'Blue')]

n = 3
[('Red', 'Red', 'Red'), ('Red', 'Red', 'Green'), ('Red', 'Red', 'Blue'), ('Red', 'Green', 'Green'), ('Red', 'Green', 'Blue'), ('Red', 'Blue', 'Blue'), ('Green', 'Green', 'Green'), ('Green', 'Green', 'Blue'), ('Green', 'Blue', 'Blue'), ('Blue', 'Blue', 'Blue')]
```

Python Code Editor:

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## Python: Tips of the Day

Inverts a dictionary with non-unique hashable values:

Example:

```def tips_collect_dictionary(obj):
inv_obj = {}
for key, value in obj.items():
inv_obj.setdefault(value, list()).append(key)
return inv_obj
ages = {
"Owen": 25,
"Jhon": 25,
"Pepe": 15,
}
print(tips_collect_dictionary(ages))
```

Output:

```{25: ['Owen', 'Jhon'], 15: ['Pepe']}
```

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