lambda python
add = lambda a, b : a + b
add(3,6) ## 9lambda expressions
A lambda expression is a short block
of code which takes in parameters
and returns a value. Lambda expressions
are similar to methods, but they do
not need a name and they can be
implemented right in the body of a method.
parameter -> expression
To use more than one parameter, wrap them in parentheses:
(parameter1, parameter2) -> expression
Example
Use a lamba expression in the ArrayList's
forEach() method to print every item in the list:
import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
ArrayList<Integer> numbers = new ArrayList<Integer>();
numbers.add(5);
numbers.add(9);
numbers.add(8);
numbers.add(1);
numbers.forEach( (n) -> { System.out.println(n); } );
}
}whats a lambda
// C++ program to demonstrate lambda expression in C++
#include <bits/stdc++.h>
using namespace std;
// Function to print vector
void printVector(vector<int> v)
{
// lambda expression to print vector
for_each(v.begin(), v.end(), [](int i)
{
std::cout << i << " ";
});
cout << endl;
}
int main()
{
vector<int> v {4, 1, 3, 5, 2, 3, 1, 7};
printVector(v);
// below snippet find first number greater than 4
// find_if searches for an element for which
// function(third argument) returns true
vector<int>:: iterator p = find_if(v.begin(), v.end(), [](int i)
{
return i > 4;
});
cout << "First number greater than 4 is : " << *p << endl;
// function to sort vector, lambda expression is for sorting in
// non-decreasing order Compiler can make out return type as
// bool, but shown here just for explanation
sort(v.begin(), v.end(), [](const int& a, const int& b) -> bool
{
return a > b;
});
printVector(v);
// function to count numbers greater than or equal to 5
int count_5 = count_if(v.begin(), v.end(), [](int a)
{
return (a >= 5);
});
cout << "The number of elements greater than or equal to 5 is : "
<< count_5 << endl;
// function for removing duplicate element (after sorting all
// duplicate comes together)
p = unique(v.begin(), v.end(), [](int a, int b)
{
return a == b;
});
// resizing vector to make size equal to total different number
v.resize(distance(v.begin(), p));
printVector(v);
// accumulate function accumulate the container on the basis of
// function provided as third argument
int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int f = accumulate(arr, arr + 10, 1, [](int i, int j)
{
return i * j;
});
cout << "Factorial of 10 is : " << f << endl;
// We can also access function by storing this into variable
auto square = [](int i)
{
return i * i;
};
cout << "Square of 5 is : " << square(5) << endl;
}whats a lambda
x = lambda a, b, c, d, e, f: a + b + c + d + e + f
print(x(31231, 312, 312, 31, 12, 31))Copyright © 2021 Codeinu
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