Data representation#

Socceraction uses a tabular action-oriented data format, as opposed to the formats by commercial vendors that describe events. The distinction is that actions are a subset of events that require a player to perform the action. For example, a passing event is an action, whereas an event signifying the end of the game is not an action. Unlike all other event stream formats, we always store the same attributes for each action. Excluding optional information snippets enables us to store the data in a table and more easily apply automatic analysis tools.

Socceraction implements two versions of this action-oriented data format: SPADL and Atomic-SPADL.

Definitions#

SPADL (Soccer Player Action Description Language) represents a game as a sequence of on-the-ball actions $$[a_1, a_2, . . . , a_m]$$, where $$m$$ is the total number of actions that happened in the game. Each action is a tuple of the same twelve attributes:

Attribute

Description

game_id

the ID of the game in which the action was performed

period_id

the ID of the game period in which the action was performed

seconds

the action’s start time

player

the player who performed the action

team

the player’s team

start_x

the x location where the action started

start_y

the y location where the action started

end_x

the x location where the action ended

end_y

the y location where the action ended

action_type

the type of the action (e.g., pass, shot, dribble)

result

the result of the action (e.g., success or fail)

bodypart

the player’s body part used for the action

Start and End Locations

SPADL uses a standardized coordinate system with the origin on the bottom left of the pitch, and a uniform field of 105m x 68m. For direction of play, SPADL uses the “home team attacks to the right” convention, but this can be converted conveniently with the play_left_to_right() function such that the lower x-coordinates represent the own half of the team performing the action.

Action Type

The action type attribute can have 22 possible values. These are pass, cross, throw-in, crossed free kick, short free kick, crossed corner, short corner, take-on, foul, tackle, interception, shot, penalty shot, free kick shot, keeper save, keeper claim, keeper punch, keeper pick-up, clearance, bad touch, dribble and goal kick. A detailed definition of each action type is available here.

Result

The result attribute can either have the value success, to indicate that an action achieved it’s intended result; or the value fail, if this was not the case. An example of a successful action is a pass which reaches a teammate. An example of an unsuccessful action is a pass which goes over the sideline. Some action types can have special results. These are offside (for passes, corners and free-kicks), own goal (for shots), and yellow card and red card (for fouls).

Body Part

The body part attribute can have 4 possible values. These are foot, head, other and none. For Wyscout, which does not distinguish between the head and other body parts a special body part head/other is used.

Example#

Socceraction currently supports converters for Opta, Wyscout, and StatsBomb event stream data. The Opta converter is also compatible with derived formats, such as the ones used by WhoScored and Stats Perform. We’ll use StatsBomb data to illustrate the API, but the API of the other converters is identical.

First, we load the event stream data of the third place play-off in the 2018 FIFA World Cup between Belgium and England.

from socceraction.data.statsbomb import StatsBombLoader

df_events = SBL.events(game_id=8657)


These events can now be converted to SPADL using the convert_to_actions() function of the StatsBomb converter.

import socceraction.spadl as spadl



The obtained dataframe represents the body part, result, action type, players and teams with numeric IDs. The code below adds their corresponding names.

df_actions = (
.merge(SBL.teams(game_id=8657))
.merge(SBL.players(game_id=8657))
)


Below are the five actions in the SPADL format leading up to Belgium’s second goal.

game_id

period_id

seconds

team

player

start_x

start_y

end_x

end_y

actiontype

result

bodypart

8657

2

2179

Belgium

Witsel

37.1

44.8

53.8

48.2

pass

success

foot

8657

2

2181

Belgium

De Bruyne

53.8

48.2

70.6

42.2

dribble

success

foot

8657

2

2184

Belgium

De Bruyne

70.6

42.2

87.4

49.1

pass

success

foot

8657

2

2185

Belgium

Hazard

87.4

49.1

97.9

38.7

dribble

success

foot

8657

2

2187

Belgium

Hazard

97.9

38.7

105

37.4

shot

success

foot

Here is the same phase visualized using the matplotsoccer package

This notebook gives an example of the complete pipeline to download public StatsBomb data and convert it to the SPADL format.

Definitions#

Atomic-SPADL is an alternative version of SPADL which removes the result attribute from SPADL and adds a few new action types. Each action is a now a tuple of the following eleven attributes:

Attribute

Description

game_id

the ID of the game in which the action was performed

period_id

the ID of the game period in which the action was performed

seconds

the action’s start time

player

the player who performed the action

team

the player’s team

x

the x location where the action started

y

the y location where the action started

dx

the distance covered by the action along the x-axis

dy

the distance covered by the action along the y-axis

action_type

the type of the action (e.g., pass, shot, dribble)

bodypart

the player’s body part used for the action

In this representation, all actions are atomic in the sense that they are always completed successfully without interruption. Consequently, while SPADL treats a pass as one action consisting of both the initiation and receival of the pass, Atomic-SPADL sees giving and receiving a pass as two separate actions. Because not all passes successfully reach a teammate, Atomic-SPADL introduces an interception action if the ball was intercepted by the other team or an out event if the ball went out of play. Atomic-SPADL similarly divides shots, freekicks, and corners into two separate actions. Practically, the effect is that this representation helps to distinguish the contribution of the player who initiates the action (e.g., gives the pass) and the player who completes the action (e.g., receives the pass).

Example#

SPADL actions can be converted to their atomic version with the convert_to_atomic() function.

import socceraction.atomic.spadl as atomicspadl



This is what Belgium’s second goal against England in the third place play-off in the 2018 FIFA world cup looks like in the Atomic-SPADL format.

game_id

period_id

seconds

team

player

x

y

dx

dy

actiontype

bodypart

8657

2

2179

Belgium

Witsel

37.1

44.8

0.0

0.0

dribble

foot

8657

2

2179

Belgium

Witsel

37.1

44.8

16.8

3.4

pass

foot

8657

2

2180

Belgium

De Bruyne

53.8

48.2

0.0

0.0

receival

foot

8657

2

2181

Belgium

De Brunne

53.8

48.2

16.8

-6.0

dribble

foot

8657

2

2184

Belgium

De Bruyne

70.6

42.2

16.8

6.9

pass

foot

8657

2

2184

Belgium

Hazard

87.4

49.1

0.0

0.0

receival

foot

8657

2

2185

Belgium

Hazard

87.4

49.1

10.6

-10.3

dribble

foot

8657

2

2187

Belgium

Hazard

97.9

38.7

7.1

-1.4

shot

foot

8657

2

2187

Belgium

Hazard

105.0

37.4

0.0

0.0

goal

foot