CODEWITHSUNDEEP
pythonlist
Austin Johnson
Austin Johnson

Reputation: 747

Matching in a list of lists

I'm working on a Baseball project and I'm trying to match names of athletes from two different csv files with their corresponding stats

For example I have two list of lists that look like this:

player_stats1 = [[Clayton Kershaw, stats, more stats, more stats]]
player_stats2 = [[Clayton Kershaw, stats, more stats, more stats]]

I have an if statement that checks if the two names are the same

if player_stats1[1][1] and  player_stats1[1][2] == player_stats2[1][1] and player_stats2[1][2]:
    print('True')
else: 
    print('false')

I need to check if the names are the same and if they are append the data from players_stats2[1][0] and players_stats2[1][5] to the original list, players_stats1

I've tried 

length1 = len(player_stats1)
players_stats3 = []
i = 1
while i < length1:
    if player_stats1[1][i] and player_stats1[1][i + 1] == player_stats2[1][i] and player_stats2[1][i + 1]:
        players_stats3.append(player_stats2[i][0], player_stats2[i][5])
    else:
        print('')
        i += 1

but I keep getting an error.

IndexError: list index out of range

Upvotes: 0

Views: 57

Answers (3)

Steven Summers
Steven Summers

Reputation: 5384

You have a list of lists. So change how you are indexing.

# get the i-th list of player stats | [Clayton Kershaw, stats, more stats, more stats]
player_stats1[i]

# get the name in the i-th list of player stats
player_stats1[i][1]

In the example you have the player name as the first item so if that is correct, then it should be the following to get the name.

player_stats1[i][0]

Example

>>> lsts = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ]
>>> lsts[0][1] # first list, second item
2

There is also a problem with your original if statement.

if player_stats1[1][1] and  player_stats1[1][2] == player_stats2[1][1] and player_stats2[1][2]:
    print('True')
else: 
    print('false')

This will always print True if both your list contains "truthy" values. You instead need to compare both.

player_stats1[1][1] == player_stats2[1][1] and player_stats1[1][2] == player_stats2[1][2]

Alternatives:

You could also use zip to group your lists together and iterate through both of them at the same time.

player_stats1 = [ ["A", "B"], ["A", "C"], ["D", "A"], ["E", "E"]]
player_stats2 = [ ["A", "A"], ["D", "A"], ["A", "C"], ["E", "E"]]

res = []
for p1, p2 in zip(player_stats1, player_stats2):
    if p1[0] == p2[0] and p1[1] == p2[1]:
        res.append( (p2[0], p2[1]) )

print(res)

The downside to zip is that:

  1. Your lists much be the same side, otherwise the smaller one will be the final length of the zip since you won't be able to form pairs with the rest of the longer list.
  2. This will only compare them to the item at the corresponding index.

If you want to find all matches then you will need to loop through both comparing each of them.

res = []
for p2 in player_stats1:
    for p1 in player_stats2:
        if p1[0] == p2[0] and p1[1] == p2[1]:
            res.append( (p2[0], p2[1]) )
print(res)

Upvotes: 1

Gratus D.
Gratus D.

Reputation: 877

You have 

length1 = len(player_stats1)

But then use:

player_stats1[1][i]

How do you know player_stats1[1][i] exists?

Shouldn't you have:

length1 = len(player_stats1[1])

Additional:

length1 = len(player_stats1)
players_stats3 = []
i = 1
while i < length1:
    if player_stats1[i][1] and player_stats1[i][2] == player_stats2[i][1] and player_stats2[i][2]:
        players_stats3.append(player_stats2[i][0], player_stats2[i][5])
    else:
        print('')
        i += 1

This is assuming player_stats1 and player_stats2 are of the same length. Generally, though, it seems like the wrong solution. You should create a key/value pair out of one csv, and check against the other, because in this solution, if you have a matching player in the wrong order, you wouldn't find it.

Upvotes: 0

chris.acampos
chris.acampos

Reputation: 61

change the while i < length1 -1: because the length would be 4 but you only have list indexing up to [3]

Upvotes: 0

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