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Python: Convert a list of dictionaries into a list of values corresponding to the specified key

Python List: Exercise - 237 with Solution

Write a Python program to convert a given list of dictionaries into a list of values corresponding to the specified key.

Use a list comprehension and dict.get() to get the value of key for each dictionary in lst.

Sample Solution:

Python Code:

def pluck(lst, key):
  return [x.get(key) for x in lst]
 
simpsons = [
  { 'name': 'Areeba', 'age': 8 },
  { 'name': 'Zachariah', 'age': 36 },
  { 'name': 'Caspar', 'age': 34 },
  { 'name': 'Presley', 'age': 10 }
]
print(pluck(simpsons, 'age'))

Sample Output:

[8, 36, 34, 10]

Flowchart:

Flowchart: Convert a list of dictionaries into a list of values corresponding to the specified key.

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Python: Tips of the Day

Memory Management:

getrefcount will show how many times an object is used in the memory. It's a fantastic tool that can be used for memory management in any program and it's very convenient too.

Getrefcount will calculate the object usage at a low level ByteCode so it can tend to be higher than expected. For instance when you print a value that value is actually processed multiple times in the background inside the print function itself and getrefcount also counts the instance when the value is called with getrefcount method itself. So, it's safe to say that the count will actually always be at least 1 time higher than expected.

Here is a code to show how many times alphanumeric characters are referenced in a random code:

import sys
x_val = 20
x_val += 1

y_val = "Heritage"

x = sys.getrefcount(x_val)
y = sys.getrefcount(y_val)

print(x, y, sep="\n")

Output:

10
4