[Tutor] exercise problem

[Roelof Wobben]

 Hello,
 
Thanks for pointing this out.
 
I change it to this :
 
def add_vectors(u, v):
    """
      >>> add_vectors([1, 0], [1, 1])
      [2, 1]
      >>> add_vectors([1, 2], [1, 4])
      [2, 6]
      >>> add_vectors([1, 2, 1], [1, 4, 3])
      [2, 6, 4]
      >>> add_vectors([11, 0, -4, 5], [2, -4, 17, 0])
      [13, -4, 13, 5]
    """
    teller=1
    getal1=0
    getal2=0 
    while teller < len(u):
        getal1 = getal1 + u[teller,0] + v[teller,0]
        getal2 = getal2 + v[teller,1] + v[teller,1]
        teller=teller+1
        uitkomst2 = [getal1, getal2]
    return uitkomst2
 
uitkomst= []
vector= [[1,0], [1,1]]
v=vector[0]
u=vector[1]
print u, v
uitkomst = add_vectors(u,v)
print uitkomst          
 
But now Im getting this message :
 


Traceback (most recent call last):
File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 28, in <module>
uitkomst = add_vectors(u,v)
File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 17, in add_vectors
getal1 = getal1 + u[teller,0] + v[teller,0]TypeError: list indices must be integers, not tuple
 
Roelof
 

 


Date: Fri, 27 Aug 2010 16:20:27 +0100
Subject: Re: [Tutor] exercise problem
From: wprins at gmail.com
To: rwobben at hotmail.com
CC: tutor at python.org

Hi Roelof,

See below


On 27 August 2010 16:05, Roelof Wobben <rwobben at hotmail.com> wrote:



uitkomst = add_vectors[u,v]
 
But now I get this error message :
 

Traceback (most recent call last):File "C:\Users\wobben\workspace\oefeningen\src\test.py", line 27, in <module> 
uitkomst = add_vectors[u,v]
TypeError: 'function' object is not subscriptable
 
So it seems that I can't use vectors as a variable in a function.
Carefully compare the syntax for calling your function (as in the doctest) to what you've written above.  See the difference?  (Hint: check the type of parentheses...)

The error message is giving you a hint -- a subscriptable item is something like a list or array.  They use square brackets.  Function calls always use (round) parentheses.  To python, it looks like you're trying to subcript the function object "add_vectors", which obviously isn't possible.  Hence the message.

Regards,

Walter 
 		 	   		  
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