n00bprogrammer22 n00bprogrammer22 - 1 month ago 7
Python Question

Shifting character in list of list 1 position left or right. After shifting return true if it was possible and false if it wasn't

A random character is instructed to move 1 position left or right if this is possible and return True and if it isn't possible then return False.

Example:

#Input:

[['.', 'B', 'B', '.', '.', '.']]

move_sideways("B", "RIGHT", lot0)

#Output:

True
[['.', '.', 'B', 'B', '.', '.']]


So it was possible for both B's to move to the right one position. If one of the B's was in the first position and was instructed to move left it would return False because this would be impossible. Same if the B was in the last position and instructed to move right.

This is my code so far but I really can't figure out how to accomplish this. Maybe I would use pop

def move_sideways(symbol, direction, lst):

for symbol in range(len(lst))
lst[1:] + lst[:1]
return lst

Answer

This may not be the most efficient way to do it but it works. I'm happy to answer any questions about it but I'm going to bed soon.

def move_sideways(symbol, direction, lst):

    if symbol not in lst:
        print('symbol is not in list')
        return False

    ind = [i for i, x in enumerate(lst) if x == symbol] #retunrs a list of the index of every symbol in list [1,2] in given example

    if direction == 'RIGHT':
        if ind[-1]+1 == len(lst):                       #check to see if the right most move will go out of the list 
            return False
        for x in ind[::-1]:
            lst.insert(x+1,lst.pop(x))                  #this will pop out every symbol and insert them back in one to the right  


    if direction == 'LEFT':
        if ind[0] == 0:                                 #checks if the left most symbol is at 0
            return False 
        for x in ind:
            lst.insert(x-1,lst.pop(x))                  #this will pop out every symbol and insert them back in one to the left

    return(True,lst)                                    #return the new list and a True in a tuplit

.

>>> a = [['.', 'B', 'B', '.', '.']]
>>> print(move_sideways('B', 'RIGHT', a[0]))
(True, ['.', '.', 'B', 'B', '.'])

>>> a = [['.', 'B', 'B', '.', 'B']]
>>> print(move_sideways('B', 'RIGHT', a[0]))
False