With with Pascals Triangle Program

Expand Post »

I am writing a program in python where in the function I input a row in Pascals triangle and the function returns the NEXT row in the triangle. Below is what I have so far and am getting really frustrate...I'm new at this and bad at iterating things. Can you help me finish my program?

Python Syntax (Toggle Plain Text)
def pascnext(L):
    currentrow = []
    if L == []:
        return [1]
    if L == [1]:
        return [1,1]
    else:
        for i in L:
            currentrow[i] = L[i] + L[i-1]
            return currentrow
def pascnext(L):
    currentrow = []
    if L == []:
        return [1]
    if L == [1]:
        return [1,1]
    else:
        for i in L:
            currentrow[i] = L[i] + L[i-1]
            return currentrow

Similar Threads

pascals triangle in C++
Sierpinski triangle program in Java
Pascal Triangle program that needs to convert from C to C# in C
Pascals triangle (Functions) in C++
pascal triangle program in C++

frank_albers123

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

2 posts
since Nov 2009

Permalink

Nov 3rd, 2009

Re: With with Pascals Triangle Program

well I think you almost have it working...just a simple modification:

Python Syntax (Toggle Plain Text)
def pascnext( l ):
    currentrow = []
    #if L == []:
    if len( l ) == 0:
        return [1]
    #if L == [1]:
    if len( l ) == 1 and l[ 0 ] == 1:
        return [ 1, 1 ]
    else:
        #for i in L:
            #currentrow[i] = L[i] + L[i-1]
            #return currentrow 
        #Note that here you cannot select currentrow[ i ] because it has no elements yet
        currentrow += [ 1 ]
        for i in range( 0, len( l ) - 1 ):
            currentrow += [ l[ i ] + l[ i + 1 ] ]
        currentrow += [ 1 ]
 
    return currentrow
 
print pascnext( [ 1, 5, 10, 10, 5, 1 ] ) 
 
>>> 
[1, 6, 15, 20, 15, 6, 1]
>>>
def pascnext( l ):
    currentrow = []
    #if L == []:
    if len( l ) == 0:
        return [1]
    #if L == [1]:
    if len( l ) == 1 and l[ 0 ] == 1:
        return [ 1, 1 ]
    else:
        #for i in L:
            #currentrow[i] = L[i] + L[i-1]
            #return currentrow 
        #Note that here you cannot select currentrow[ i ] because it has no elements yet
        currentrow += [ 1 ]
        for i in range( 0, len( l ) - 1 ):
            currentrow += [ l[ i ] + l[ i + 1 ] ]
        currentrow += [ 1 ]

    return currentrow

print pascnext( [ 1, 5, 10, 10, 5, 1 ] ) 

>>> 
[1, 6, 15, 20, 15, 6, 1]
>>>

Last edited by masterofpuppets; Nov 3rd, 2009 at 6:34 pm.

masterofpuppets

Reputation Points: 20

Solved Threads: 74

Posting Whiz in Training

Offline

272 posts
since Jul 2009

Permalink

Nov 3rd, 2009

Re: With with Pascals Triangle Program

just wanted to post another test result:

Python Syntax (Toggle Plain Text)
l = []
for n in range( 10 ):
    next = pascnext( l )
    print next
    l = next
 
>>> 
[1]
[1, 1]
[1, 2, 1]
[1, 3, 3, 1]
[1, 4, 6, 4, 1]
[1, 5, 10, 10, 5, 1]
[1, 6, 15, 20, 15, 6, 1]
[1, 7, 21, 35, 35, 21, 7, 1]
[1, 8, 28, 56, 70, 56, 28, 8, 1]
[1, 9, 36, 84, 126, 126, 84, 36, 9, 1]
>>>
l = []
for n in range( 10 ):
    next = pascnext( l )
    print next
    l = next

>>> 
[1]
[1, 1]
[1, 2, 1]
[1, 3, 3, 1]
[1, 4, 6, 4, 1]
[1, 5, 10, 10, 5, 1]
[1, 6, 15, 20, 15, 6, 1]
[1, 7, 21, 35, 35, 21, 7, 1]
[1, 8, 28, 56, 70, 56, 28, 8, 1]
[1, 9, 36, 84, 126, 126, 84, 36, 9, 1]
>>>

masterofpuppets

Reputation Points: 20

Solved Threads: 74

Posting Whiz in Training

Offline

272 posts
since Jul 2009

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Python Forum Timeline: Pygame question2

Next Thread in Python Forum Timeline: File to dictionary

DaniWeb Message

Cancel Changes

User Name
Password