﻿ Python: Grouping a sequence of key-value pairs into a dictionary of lists - w3resource

# Python: Grouping a sequence of key-value pairs into a dictionary of lists

## Python dictionary: Exercise-46 with Solution

Write a Python program to create a dictionary grouping a sequence of key-value pairs into a dictionary of lists.

Sample Solution:

Python Code:

``````def grouping_dictionary(l):
result = {}
for k, v in l:
result.setdefault(k, []).append(v)
return result
colors = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
print("Original list:")
print(colors)
print("\nGrouping a sequence of key-value pairs into a dictionary of lists:")
print(grouping_dictionary(colors))
```
```

Sample Output:

```Original list:
[('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]

Grouping a sequence of key-value pairs into a dictionary of lists:
{'yellow': [1, 3], 'blue': [2, 4], 'red': [1]}
```

Pictorial Presentation:

Flowchart:

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## Python: Tips of the Day

Invokes the provided function after ms milliseconds:

Example:

```from time import sleep

def tips_delay(fn, ms, *args):
sleep(ms / 1000)
return fn(*args)
print(tips_delay(
lambda x: print(x),
1000,
'w3r'
))
```

Output:

```w3r
None
```