Question

How would I write the definition for this
def shift(my_list):
"Shifts the list [x1,x2,...,xn] to [x2,x3,...,xn,x1]."

Answer 1

If you don't get what i am trying to do, i am defining a function that will shift the list to the right moving the first element to the end.

Answer 2

You can try this - it may not be pretty, but it works. I threw in print statements so you could see whats happening.


def shifting():
a = [1,2,3,4]
for i in range(5):
print "Original List:", a
b = a[1:]
b.append(a[0])
print "Ammended List:", b
print
a = b

Answer 3

You could do it just once, or as many times as you wish, by changing the range(x).

Answer 4

thank you and i have one more question to ask which ocw course is better http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00-introduction-to-computer-science-and-programming-fall-2008/index.htm or http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-189-a-gentle-introduction-to-programming-using-python-january-iap-2010/

Answer 5

I am using the second one right now but it is a little confusing because there giving us problems they never taught like the one i asked you. So i was wondering if the one for this study board is better?

Answer 6

I don't know the other course...sorry.

Answer 7

Oh okay but have you had any problems with the course your using. Where the stuff asked for hasn't been taught or is it a good course?

Answer 8

It is a very good course so far. So far, everything matches up quite good. Of course you need to do extra reading for some things, but that is to be expected from a free online course. The teacher-pupil aspect does not exist, so you need to be willing to work a little, and be autonomous.

Answer 9

Thank You

Answer 10

def shift(aList)
aList.append(aList[0])
del aList[0]
return aList

Answer 11

nice!

Answer 12

:) I'm really warming to lists.

Answer 13

Thank You. I actually came up with the exact same script last night. I guess i was just cramming my brain too much because i took an hour break. Then I laid down and as I was laying down going to sleep i was like wouldn't it be easier to just take the first element and move to end using append then delete the first.

Answer 14

A couple of things to consider.. Do you wish to modify the list in place, or return a new list constructed by shifting the old one. In general I would recommend the latter since it has fewer side effects.



#does not modify

def shift(thelist):

return thelist[1:] + thelist[0]



#modifies

def inplace_shift(thelist):

thelist.append(thelist.pop(0))

Answer 15

Oh that's nice polpak! I hadn't thought about how it would modify (or not) the list...I tried to break down Keen's function but found it really hard, now with your input I am thinking about how much I don't know about programming, :-) and I think I will try simplifying my own work. Thanks!