length (snippet)

Python example 'length'

Functions in program:

• def length(ar, is_ap = False, is_gp = False, big_data = False, data_outline = []):

Modules used in program:

• import math

length

Python beginners example: length

#!/usr/bin/python
# -*- coding: utf-8 -*-

import math

# Length of array(number of elements in array)
# is simple algorithm
#  Iterates through array
#  at each iteration (count) variable
#  is incremented
# 
# This solution is ideal for small array
# But not that good for bigger array's

# There are many ways to do same thing
# but always go with solution that is
# simple, and has least instructions
# for computer to execute, making
# process faster

# is_ap parameter indicates weather array
# is an arithmetic progression or not
#
# Similarly, 
# is_gp indicates weather array is an geometric progression or not
# If array is either ap or gp then it's length can be
# found by derivation of it's general term formula
# e.g. ap's general term,
# tn = a + (n - 1)d
# thus, n = (tn - a) / d + 1 

def length(ar, is_ap = False, is_gp = False, big_data = False, data_outline = []):
    # Length of data if it is an arithmetic progression
    # using derived formula, n = (tn - a) / d + 1
    if is_ap:
        return ((ar[-1] - ar[0]) / (ar[1] - ar[0])) + 1

    # Length of data if it is an geometric progression
    # using derived formula, n = ((log base 10 an / a1) / log 10 r) + 1
    elif is_gp:
        # length is never a float
        return int(math.log10((ar[-1] / ar[0])) / math.log10((ar[1] / ar[0])) + 1)

    # Length of big data using data outline
    # data outline is selective elements to be counted from entire
    # data
    elif big_data:
        count = 0
        for element in data_outline:
            count += ar.count(element)
        return count 

    # Sequential counting
    # of elements in array
    else:
        res = 0
        for item in ar:
            res += 1
        return res 


# Test
# Geometric progression Test
if length([1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096], None, is_gp = True) == 13:
    print("\nLength of geometric progression: " + str(13))
    print("--> geometric progression counting works!\n")
else:
    print("Something's wrong with gp feature")

# Arithmetic progression test
if length([1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43], is_ap = True) == 15:
    print("Length of arithmetic progression: " + str(15))
    print("--> arithmetic progression counting works!\n")
else:
    print("Something's wrong with ap feature")

# Big data test
# Passing only useful numbers in outline array
if length([1, 1, 4, 5, 7, 1, 9, 5, 2, 4, 3, 5, 9], None, None, True, [1, 4, 5, 7, 9]) == 11:
    print("Length of arithmetic progression: " + str(11))
    print("--> big data counting works!\n")
else:
    print("Something's wrong with ap feature")

# Small data
print("Length: " + str(length([1, 1, 2, 3, 5, 8, 13, 21, 34, 55])))
print("Everything Works!\n")

Useful links

• Learn Python: https://pythonbasics.org
• Download Python: https://python.org