CODEWITHSUNDEEP
pythonintegercomparepython-3.3digits
unintendedjoy
unintendedjoy

Reputation: 289

How do I extract short digit sequences from two different integers and compare them?

I'm new to Python and I'm having trouble with one of my assignment.

So the question is: I have to obtain two positive integers from the user (one longer and one shorter). Then I have to loop through the longer integer (from left to right) and to check to see if the shorter integer appears inside the longer integer. And I have to report the position of the matches and the number of matches.
*I am not allowed to use strings and list to do this assignment ):

Examples of the result is supposed to be like this:

Eg 1.
Input a positive longer integer: 123456789
Input a positive shorter integer: 123
Found a match at position 0
End: found 1 matches

Eg 2.
Input a positive longer integer: 123456789
Input a positive shorter integer: 789
Found a match at position 6
End: found 1 matches

Eg 3.
Input a positive longer integer: 12312312312231222
Input a positive shorter integer: 22
Found a match at position 10
Found a match at position 14
Found a match at position 15
End: found 3 matches

Eg 4.
Input a positive longer integer: 12312312312231222
Input a positive shorter integer: 55
End: cannot find any match

So what I did so far: 

# Ask user for positve longer integer number
longInt = int(input("Input a positive longer integer: "))

# Ask user for positive shorter integer number 
shortInt = int(input("Input a positive shorter integer: "))

# Count number of digits in both longer and shorter integer numbers
import math
longLength = int(math.log10(longInt))+1
shortLength = int (math.log10(shortInt))+1

for i in range(0,longLength):
    for x in range(0,shortLength):
        while (longLength > 0):
            longDigit = longInt % 10 **(longLength) // 10**(longLength-1)
            longLength-=1
            print (longDigit)
        while (shortLength > 0):
            shortDigit = shortInt % 10**(shortLength) // 10**(shortLength-1)
            shortLength-=1
            print (shortDigit)

Please do help! Thanks! (:

Upvotes: 2

Views: 270

Answers (2)

dawg
dawg

Reputation: 103844

You could do something along these lines:

def i2l(i):
    rtr=[]
    while i:
        rtr.insert(0, i%10)
        i//=10
    return rtr

longer=int(input("Input a positive longer integer: "))    
shorter=int(input("Input a positive shorter integer: "))

ll=i2l(longer)   
ls=i2l(shorter)

answer=[]
for idx in [i for i,e in enumerate(ll) if e==ls[0]]:    
    try:
        all_good=all(ll[i+idx]==e for i,e in enumerate(ls))    
    except IndexError:
        all_good=False 
    if all_good:
        answer.append(idx)

if answer:
    s='index' if len(answer)==1 else 'indices'
    print '{} found in {} at {} {}'.format(shorter,longer,s,answer)
else:
    print '{} not found in {}'.format(shorter,longer)

Now run it:

Input a positive longer integer: 12312312312231222
Input a positive shorter integer: 22
22 found in 12312312312231222 at indices [10, 14, 15]

Input a positive longer integer: 12312312312231222
Input a positive shorter integer: 4
4 not found in 12312312312231222

Upvotes: 0

lucasg
lucasg

Reputation: 11002

You just need to offset your longInt several times to extract all the shortInt-length integers ( like bit-shifting, but with power of tens' instead of twos').

import math

# Ask user for positve longer integer number
longInt = 123456789 

# Ask user for positive shorter integer number 
shortInt = 1234

# Count number of digits in both longer and shorter integer numbers

longLength  = int( math.log10(longInt) )+1
shortLength = int( math.log10(shortInt))+1

for offset in range(0, longLength):
  subInt = (longInt// 10**(offset)) % 10 **(shortLength) 
  print(subInt)

Result :

6789 5678 4567 3456 2345 1234 123 12 1

Upvotes: 0

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