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
All original content copyright, © 2011-2021. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.
