Calculator Python: Lambda Functions
Introduction to Lambda Functions
Lambda functions are a quick, one expression, one line, python function. Lambda functions do not require to be named though they can be named for future use if desired.
The syntax for lambda functions are:
One argument:
lambda argument : expression
Two or more arguments:
lambda arg1, arg2, arg3, ... : expression
The expression must return one result.
The quick, versatile of lambda functions are make lambda functions one of the most popular programming tools.
Filter, Map, and Reduce
Filter: uses a lambda function to filter out elements of a list and array using criteria. For a list, the list command must be used to turn the result into an actual list.
Syntax using Lambda and List:
list(filter(lambda arguments : expression))
Map: uses a lambda function to apply a function to each element of a list. Like filter, the list command must be used to turn the result into an actual list.
Syntax using Lambda and Map:
list(map(lambda arguments : expression))
Reduce: uses a lambda function to use two or more arguments in a recursive function.
Syntax using Lambda:
reduce((lambda arguments : expressions), list)
Note, as of August 31, 2021, that the reduce command is NOT available on any calculator, only on full version of Python 3. This may change with future updates.
HP Prime: lambda, filter, map
Casio fx-CG 50 and fx-9750GIII: lambda, map
Numworks: lambda, filter, map
TI-84 Plus CE Python: lambda, filter, map
TI-Nspire CX II Python: lambda, filter, map
Nuwmorks Sample Python File: introlambda.py
from math import *
from random import *
# lambda test
n=randint(10,9999)
tens=lambda x:int(x/10)%10
hunds=lambda x:int(x/100)%10
thous=lambda x:int(x/1000)%10
print(n)
print(tens(n))
print(hunds(n))
print(thous(n))
print("List:")
l1=[1,2,3,4,5,6]
print(l1)
print("Filter demonstration")
print("Greater than 3")
l2=list(filter(lambda x:x>3,l1))
print(l2)
print("Odd numbers")
l3=list(filter(lambda x:x%2!=0,l1))
print(l3)
print("Map demonstration")
print("Triple the numbers")
l4=list(map(lambda x:3*x,l1))
print(l4)
print("exp(x)-1")
l5=list(map(lambda x:exp(x)-1,l1))
print(l5)
Sources
Maina, Susan "Lambda Functions with Practical Examples in Python" Towards Data Science (membership blog with limited free access per month) https://towardsdatascience.com/lambda-functions-with-practical-examples-in-python-45934f3653a8 Retrieved August 29, 2021
Simplilearn "Learn Lambda in Python with Syntax and Examples" April 28, 2021. https://www.simplilearn.com/tutorials/python-tutorial/lambda-in-python Retrieved August 29, 2021
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