Question

Having some difficulty here. My goal is to read numbers from a column in a gameboard and print these numbers out as a specific list. I don’t have much experience with lists and neither do I grasp the concept properly so I’m having some difficulty with getting them to work. So far, all I could muster was this:

def getColumn ():
    for i in range (0, 9):
        row = datalist[i]
        column = row[x]
        column.append[i]

Doesn’t seem to work properly, could anyone point out why? I would really appreciate it!

Thanks!

Answer 1

Here’s a version that tweaks your original code:

datalist = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

def getColumn(col_num, data):
    column = []
    for i in range (0, len(data)):
        row = data[i]
        column.append(row[col_num])
    return column

Which gives:

getColumn(1, datalist)
Out[9]: [2, 5, 8]

Some problems with your original code:

• You didn’t have any way to tell getColumn which column you wanted- you need to make this an argument of your function
• getColumn relied on there being a global variable called datalist. Passing the data as an argument is safer.
• datalist had to have exactly nine rows, or you’d get errors or wouldn’t get the full column returned.