docstr: Convert bounding box to format `(center x, center y, aspect ratio,
  height)`, where the aspect ratio is `width / height`.
docstr_tok: ["Convert","bounding","box","to","format","`","(","center","x",",","center","y",",","aspect","ratio",",","height",")","`",",","where","the","aspect","ratio","is","`","width","\/","height","`","."]
code: def tlwh_to_xyah(tlwh):
      """Convert bounding box to format `(center x, center y, aspect ratio,
      height)`, where the aspect ratio is `width / height`.
      """
      ret = np.asarray(tlwh).copy()
      ret[:2] += ret[2:] / 2
      ret[2] /= ret[3]
      return ret
  
imports: import numpy
  from collections import defaultdict
  from collections import deque, OrderedDict
  from ..matching import jde_matching
  from ppdet.core.workspace import register, serializable
  import warnings
label_desc: Use image node_id 12 for calling the STrack obj's underlying member method code with example usage: obj.tlwh_to_xyah(tlwh) and returns: ret