// js
//***************************************************************************
// USE CASE
//
// SUM first 100 even integers
//***************************************************************************
n = [...Array(100).keys()] // get indexes starting at 0
.map(_ => ++_) // inc
even = n.filter(_ => !(_ % 2))
evenSum = even.reduce((acc, _) => acc + _, 0)
// (element, index) =>
> A = {a: [1, 2], b: ['one', 'two']}
> A.a.map((elem, index) => elem + ';' + A.b[index])
["1;one", "2;two"]
//***************************************************************************
// USE CASE
//
// Create strings with values concatenated from the different arrays, in that
// the first element of the first array is concatenated with all the elements
// of the second, and so forth.
//***************************************************************************
> A = []
> "abcdefghijklmnopqrstuvwxyz".split('').forEach(char => A.push(char)) // alphabet
> B = [...Array(A.length).keys()].map(_ => ++_) // integers 1 to alphabet length
> index = 1
> C.forEach(_ => CD[_] = D[index++])
> A.map(a =>
B.map(b =>
id++ + ';' + a + ';' + b
)).reduce((acc, e) => acc.concat(e), [])
["703;a;1", …]# python
#***************************************************************************
# USE CASE
#
# SUM first 100 even integers
#***************************************************************************
from functools import reduce
n = map(lambda _ : _, range(100))
even = filter( lambda _ : _ % 2 == 0, n )
evenSum = reduce(lambda x, y : x + y, even)
#***************************************************************************
> B = np.arange(1, 11)
> np.array(list(map(lambda _: _ > 5, B)))
array([False, False, False, False, False, True, True, True, True,
True])
> B > 5
array([False, False, False, False, False, True, True, True, True,
True])
> B[B > 5]
array([ 6, 7, 8, 9, 10])
> np.array(list(filter(lambda _: _ > 5, B)))
array([ 6, 7, 8, 9, 10])
