print an element of a list(let's say 3 lines and 2 rows,two-dimensional list) .what i'm doing wrong? for python

Question

playerscoins=[[10 for i in range(2)]for j in range(3)]

def currentbalance(coins):
    print("Current balance:")
    for i in range(3):
        print("Player %i has %i coins." % i , coins[i,0])

currentbalance(playerscoins)

Current balance:
Traceback (most recent call last):
  File "<pyshell#83>", line 1, in <module>
    currentbalance(playerscoins)
  File "<pyshell#82>", line 4, in currentbalance
    print("Player %i has %i coins." % i , coins[i,0])
TypeError: not enough arguments for format string

Answer 1

There are two things wrong with your code:

1. You're trying to use a tuple as an index to coins. Since coins is a list of lists, you want to do coins[i] to get the i-th list and then [0] to get the first element of that list, making the expression coins[i][0].
2. You're not passing a tuple to the format string. Since there are no parens around i, coins[i][0], the second part is getting interpreted as another arg to print rather than as another part of the operand to %.

Fixing those errors would look like:

for i in range(3):
    print("Player %i has %i coins." % (i, coins[i][0]))

A less confusing way to do this (if you're on Python 3, which everyone should be IMO) is to use f-strings rather than the % operator:

for i in range(3):
    print(f"Player {i} has {coins[i][0]} coins.")

You could also simplify the whole problem of how to index the lists by using enumerate to iterate over each row of coins. This also saves you from having to hard-code in the number of rows:

for p, row in enumerate(coins):
    print(f"Player {p} has {row[0]} coins.")