Global name is not defined python recursion

In the line [l1 = sortList[head]] for recursion, I get NameError: global name 'sortList' is not defined. Could anyone point out where I did wrong?

class Solution:
    # @param head, a ListNode
    # @return a ListNode

    def sortList[self, head]:
        if head == None or head.next == None:
            return head

        slow = head
        fast = head

        while fast != None and fast.next != None:
            slow = slow.next
            fast = fast.next.next
        fast = slow
        slow = slow.next
        fast.next = None
        l1 = sortList[head]
        l2 = sortList[slow]
        l = mergeTwoLists[l1, l2]
        return l

Korem

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asked Jun 18, 2014 at 17:46

5

sortList is a method of Solution, and doesn't exist independently. Use:

self.sortList[head]

and it would work.

answered Jun 18, 2014 at 17:49

KoremKorem

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You have not imported any function named sortList, so there only exists a sortList that can be called on a Solution object.

Use self.sortList. self is a variable used in python to refer to the current object. Much like this in other languages.

answered Jun 18, 2014 at 17:51

AlexAlex

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Change l1 = sortList[head] to l1 = self.sortList[head], and l2 = sortList[slow] to l2 = self.sortList[slow]. sortList is defined in the Solution class and does not exist globally, that's why you need self to refer to the current Solution object.

answered Jun 18, 2014 at 17:49

timgebtimgeb

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I want to make a player that can shoot bullets. To do this i tried defining a shoot function that gets called when space bar is pressed. The function looks like this [p is the player object btw]:

class bullet:
    def __init__[self]:
        self.x = None
        self.y = None
        self.radius = 10
        self.shooting = False
        self.speed = 5

    def shoot[self]:
        self.shooting = True
        if  self.shooting == True:
            self.x = [p.x + 60]
            self.y = [p.y + 25]
            self.x += self.speed
            self.y += self.speed
            pygame.draw.circle[d, [0, 0, 0], [self.x, self.y], self.radius]

        shoot[]

I was hoping that the function would keep calling itself and the bullet would keep moving forward. However what actually happens is when i press space, it gives me an error

    shoot[]
NameError: name 'shoot' is not defined

How i called the function:

while True:
    d.fill[[98, 98, 98]]
    p.draw[]

    for event in pygame.event.get[]:
        pass

    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_SPACE:
            b.shoot[]

Something i observed is that if i remove the recursion shoot[] at the end of the shoot[] function, it runs but the bullet stays in the same place as long as the space is being held down[as expected as recursion was removed]. How can i fix this problem? Thanks

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Answer

shoot is not a function, strictly speaking. It’s an instance method, and must be invoked from a bullet object. You need to use

for recursion.

However, this is a poor way to keep the bullet moving. This is a job for a loop. Recursion is best used when you’re calling the routine with a smaller version of the problem; this is just a continuance.

    while self.shooting == True:
        self.x = [p.x + 60]
        self.y = [p.y + 25]
        self.x += self.speed
        self.y += self.speed
        pygame.draw.circle[d, [0, 0, 0], [self.x, self.y], self.radius]

This raises the question of how you intend to quit moving the bullet. You need something like

        self.shooting = [self.x