Question

Sequential Search Algorithm

Python Programming

Objectives
----------

* sequential search - design, analyze, implement, test, time
* continue practicing previously learned skills:
  algorithm analysis, graphing with theoretical prediction curves


Implementation
--------------
Write a function named sequential_search.
It must have two parameters, a list to search and a value to search for.
It must return either the index of the value within the list or -1 if
the value is not found in the list.

Your search function should NOT print anything.
If you have debugging or testing print statements in the function, 
comment them out before doing any timing.


Testing
-------
Create a list of five random numbers. Use randint, don't hardcode.
Demonstrate your algorithm finding each of the numbers.
in the list. Then look for a number not in the list.
You may write a testing function if you wish, params and
returns up to you, or do all testing in the main program.

expected output (use different numbers than in the example)


       numbers [5, 8, 3, 11, -2]

       searching for 5
       expected index: 0
       returned index: 0
       test passed: YES

       searching for 8
       expected index: 1
       returned index: 1
       test passed: YES

       searching for 3
       expected index: 2
       returned index: 2
       test passed: YES

       searching for 11
       expected index: 3
       returned index: 3
       test passed: YES

       searching for -2
       expected index: 4
       returned index: 4
       test passed: YES

       searching for 100
       expected index: -1
       returned index: -1
       test passed: YES

       passed 6 out of 6 tests


Timing
------
Make sure you are timing the WORST CASE for sequential search.
That means look for a value you know is not in the list.

Do NOT include list creation in your timing. Do NOT include any input.
Only time sequential search. If you laptop is very fast, you might
have to time many calls to sequential search, not just one call.
To get the time for just one call, divide by the number of calls.

example:


       repetition_count = 10000

       time_start = time()

       for rep in range( repetition_count ):
           ind = sequential_search( value, my_list )

       time_end = time()
       time_all_reps = time_end - time_start
       time_one_rep = time_all_reps / repetition_count


You may create the timing table in your program so you don't have to
type it up in Word. If you do that, your table must have neat columns
that line up and 3 or 4 significant figures after leading zeros.

example:


    list     single        comparison time
    length   search time   or C estimate

      2000   0.000205      1.025e-07    
      4000   0.0004391     1.098e-07    
      6000   0.0006798     1.133e-07    
      8000   0.0008866     1.108e-07    
     10000   0.001112      1.112e-07    

Answer 1

# A Python program that uses Logical Not or ! on boolean

import random

def sequential_search(alist, item):

pos = 0

while pos < len(alist):

if alist[pos] == item:

return pos

else:

pos = pos+1

return -1

numbers= []

for i in range (5):

numbers.append(random.randint(0, 100))

  

print(numbers)

for i in range (5):

print(sequential_search(numbers,random.randint(0, 100)))

ganonymous/untitled input clear run share save Python 3.6.1 (default, Dec 2015, 13:05:11) [GCC 4.8.2] on linux # A Python program that uses Logical Not or ! on boolean 2 import random 3 import time 4 5 def sequential_search(alist, item) [31, 42, 74, 79, 97] 4 pos-e 7 while pos < len(alist): if alist[pos]item: return pos 10 else: pospos+1 12 13 14 15 16 numbers- [ 17for i in range (5) 18 19 20 print (numbers) 21 22 for i in range (5): 23 print (sequential_search(numbers,random.randint (, 100)b) 24 25 return-1 numbers.append (random.randint (e, 100)) Activate Windows Go to Settings to activate W