deletions | additions       diff --git a/subsubsection_Description_We_used_a__.tex b/subsubsection_Description_We_used_a__.tex  index 783fe42..23a7eb0 100644  --- a/subsubsection_Description_We_used_a__.tex  +++ b/subsubsection_Description_We_used_a__.tex 
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Data are read and extracted with a frequency of 25 Hz which correspond to the best frequency we could have if we were extracting directly from the videos of the soccer match. As each players is equipped with several sensor we combine their data to have one and only one trajectory per player or ball.  Sometimes some data have been missed, we cope with this problem interpolating data so as to maintain synchronization between the different trajectories.  We also decide to exclude the ball trajectory because it very often goes out of the play and also because it occurs a lot of ball change. When a player goes out of the field we can't neither treat it as usual with positions out of the field because it would be non sense nor stop extracting the data because it would break the continuity of extracted player's position. Whereas the displacement of a player going and fetching the ball out of the field is non sense, the paths of other players at this while bring relevant information. Thus in this case we just consider that the outside player remain at the last read position on the field with a null acceleration. We also decide to exclude the ball trajectory because it very often goes out of the play and also because it occurs a lot of ball change.