PySport/kloppy

Opta deserializer incorrectly sets end coordinate of saved shots

Closed this issue · 2 comments

probberechts commented

If a shot has qualifier "102" (i.e., a goal mouth y-coordinate), the Opta deserializer automatically sets the end-x coordinate of the shot to 100 and uses the value of the qualifier to set the shot's end-y coordinate.

kloppy/kloppy/infra/serializers/event/opta/deserializer.py

Lines 505 to 507 in 096f959

if 102 in raw_qualifiers:
x = float(100)
y = float(raw_qualifiers[102])

This seems incorrect if the shot was not saved on the goalline. In the Opta data stream, saved shots have two y-coordinates. One coordinate for the location where the shot was blocked and one coordinate which (I assume) is based on the projection of the shot on the goal mouth.

  <Event id="1124226663" event_id="435" type_id="15" period_id="1" min="38" sec="47" player_id="14464" team_id="174" outcome="1" x="92.6" y="57.9" timestamp="2018-08-20T21:39:10.635">
    <Q id="1201627127" qualifier_id="17" />
    <Q id="1138078681" qualifier_id="22" />
    <Q id="1370931446" qualifier_id="102" value="52.1" />  <!-- Goal mouth y-coordinate -->
    <Q id="1083530127" qualifier_id="103" value="18.4" /> <!-- Goal mouth z-coordinate -->
    <Q id="1591211723" qualifier_id="76" />
    <Q id="1133507498" qualifier_id="56" value="Center" />
    <Q id="1898374933" qualifier_id="55" value="433" />
    <Q id="1208960709" qualifier_id="29" />
    <Q id="1463101346" qualifier_id="328" />
    <Q id="1713152233" qualifier_id="154" />
    <Q id="1320398977" qualifier_id="147" value="52.5" />  <!-- Blocked y-coordinate -->
    <Q id="1946686767" qualifier_id="146" value="99.1" />  <!-- Blocked x-coordinate -->
    <Q id="2107391537" qualifier_id="233" value="289" />
    <Q id="2102498620" qualifier_id="15" /> 
  </Event>

I think the "blocked coordinates" should be used here for the x-coordinate at least. That would be consistent with the StatsBomb parser. I am not sure what to do with the goal mouth coordinates. Do we add an extra attribute (intended_coordinates) for shots, drop the y-coordinate and use the z-coordinate as is, drop the z-coordinate, ...

I am also wondering how the y-and z-coordinates are defined by StatsBomb for saved shots. Are they also projected on the goal mouth?

JanVanHaaren commented

I am also wondering how the y-and z-coordinates are defined by StatsBomb for saved shots. Are they also projected on the goal mouth?

My understanding is that StatsBomb records the x-, y-, and z-coordinates of the location where the goalkeeper saved the shot.

Example 1: https://youtu.be/CIiGAh4H6Js?si=TAbFdNoTaAMxXcMG&t=56

"location": [
    99.5,
    41.6,
    0.0
]

"end_location": [
    116.4,
    40.8,
    2.0
]

Example 2: https://youtu.be/CIiGAh4H6Js?si=Ka8dL3ySS0OhXQK_&t=163

"location": [
    111.3,
    28.9,
    0.33
],

"end_location": [
    113.8,
    31.1,
    0.8
],
  • 👍1
JanVanHaaren commented

In the Opta data stream, saved shots have two y-coordinates. One coordinate for the location where the shot was blocked and one coordinate which (I assume) is based on the projection of the shot on the goal mouth.

The Stats Perform documentation provides the following descriptions for qualifiers 102, 103, 146, 147, 230 and 231.

  • 102 - Goalmouth Y Coordinate: "The Y-coordinate (0-100) of where the shot/ball crossed/was projected to cross the goal line."
  • 103 - Goalmouth Z Coordinate: "The Z-coordinate (0-100) for the height at which a shot/the ball crossed/was projected to cross the goal line."
  • 146 - Blocked X Coordinate: "The X-coordinate where a shot is blocked or an off target attempt is touched by an opposition player."
  • 147 - Blocked Y Coordinate: "The Y-coordinate where a shot is blocked or an off target attempt is touched by an opposition player."
  • 230 - GK X Coordinate: "The X-coordinate for the position of the goalkeeper (GK) for the shot."
  • 231 - GK Y Coordinate: "The Y-coordinate for the position of the goalkeeper (GK) for the shot."

However, qualifiers 230 and 231 come with the following note.

This can be shown for live data (for example, for eventTypeIds 14 and 16). However, from June 2020 it can also be added post-match to Blocked Shot, Miss (not past the goal line) and all shot events, but only for some competitions. When added as a post-match qualifier it is only shown once the post-match analysis is complete.

  • 👍1