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+--- Thread: 2d Array adds last element to entire list (/thread-31047.html)
2d Array adds last element to entire list - waiteup - Nov-19-2020
Good Afternoon!
First time poster!
I keep running into this simple problem when trying to fill my 2d array from my SQL. For some reason it will not store the values into my variables. I am really not too sure what else to do here? It seems painfully obvious and is probably staring at me right in the face.
Here is my function -
def GetPlayerData(conn,cur):
rows, cols = (6, 6)
Players = [[0]*cols]*rows
cur.execute('SELECT * FROM Players')
for x in range (1,6):
nextline = cur.fetchone()
Players[x][0]= nextline['Players']
Players[x][1]= nextline['Total_Cash']
Players[x][2]= nextline['Risk_Level']
print(Players[x][0])
print(Players[2][2])
return PlayersMy first print(Players[x][0]) Displays the entire list as it cycles through x.My second print(Players[2][2]) shows the last 'players' in the list. every single players[1-5] is stored as the last item in my database.
Thank you
RE: 2d Array adds last element to entire list - waiteup - Nov-19-2020
After looking at the screen for 4 hours, I came to the realization that I was making 5 different arrays and I could just use
Player = {}
Player[1,0] instead of Player [1][1]Thanks guys!
RE: 2d Array adds last element to entire list - bowlofred - Nov-19-2020
Your initial problem was that you were not making different lists, but just several copies of one list. The construction:
[[]] * num takes the inside list and makes num references to it, but they're all the same list. So each time through was overwriting the previous trips through the loop.>>> players = [[0] * 4] * 3 >>> players [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]] >>> players[0][1] = "x" >>> players [[0, 'x', 0, 0], [0, 'x', 0, 0], [0, 'x', 0, 0]]For this to work, you'd need to make different lists.
>>> players = [[0] * 4 for x in range(3)] >>> players [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]] >>> players[0][1] = "x" >>> players [[0, 'x', 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]