List comprehension (again)

Game Engine Game Engine Support and Discussion
1

Hi all

Another list comprehension question: I am making a racing position indicator that reads
what place a player is in the race- like 2 / 4 (player is second out of four).

Now, I can easily get how many racers there are (via len), and I can easily sort the racers into order, but I have a problem in that I need to return the position of the player in a list (so I can use the .index() command).

Psuedocode:



sce = bge.logic.getCurrentScene() 

objList = sce.objects 

Players = [ob for ob in sce.objects if 'distance' in ob]

Players.sort(key=lambda sortkey: sortkey['distance'],reverse=True)

print(Players)

Players_len = len(Players) # establishes how many racers

Position = Players.sort(key=lambda sortkey: sortkey['distance'],reverse=True).index(objList['Cube'])

print(Position)

The last line is the problem: I can sort the racers via the [‘distance’] property, but I need to get the position of the players object in the list to return a number for the HUD.

The annoying thing is the list returns the objects names (like Cube, Cube001) but I cannot use them to get their position in the list (via .index(objList[‘Cube’]) or equivalent).

Can anyone shed some light on this?

Many thanks

Paul

2

I was able to setup a test similar to what you described and it appears to work on the default scene:

import bge

scene = bge.logic.getCurrentScene()
print(scene.objects.index(scene.objects['Camera']))

This prints out the index of the camera in the object list correctly. Also, why do you sort the list twice?

The sort method probably is returning None, so you are trying to call None’s index method (which it doesn’t have). Are you getting some kind of error?

3

I think I am confusing myself, but this is what I need to find:

I sort the players by a property [distance], so I would get a list like [player1,player2,player3] etc. Now in this example I only want to get player 2s position in the list regardless of what position it might be ([0], [1] or [2]) and use that as an integer (for a race position property)- so when I use len(Players) to get the total players I would hopefully get Player2 current position out of the racers, which is 2nd out of 3 (2/3).

I can do the initial sort, and I can get the number of racers. I just need a way to say ‘only report what Player 2s position on the list is’. I can do the reverse (Print(Position2) which gives me whoever is second just not the other way round.

4

I think because you are calling .index on the end of the sort method. The sort method operates on the list and doesn’t return anything, so:

Players.sort(key=lambda car: car['distance'], reverse=True)
print(Players.index(objList['Cube']))
5

Thanks guys! I would mark this SOLVED but my work computer uses IE6 and not everything is showing up.

6

without “lambda”?
Players.sort(key=car, car[‘distance’], reverse=True)
in my blender get error (syntax error)

must write this:

Players.sort(key=lambda car : car[‘distance’], reverse=True)
(without comma)

7

Sorry, with lambda. I’ll edit that in.