added maximum threshold (#505)

Co-authored-by: NiekWielders <c4072114@newcastle.ac.uk>

Author: NiekWielders

autolens/analysis/result.py

@@ -263,6 +263,7 @@ def positions_likelihood_from(
         self,
         factor=1.0,
         minimum_threshold=None,
+        maximum_threshold=None,
         positions: Optional[aa.Grid2DIrregular] = None,
         mass_centre_radial_distance_min: float = None,
         plane_redshift: Optional[float] = None,
@@ -289,6 +290,9 @@ def positions_likelihood_from(
         minimum_threshold
             The output threshold is rounded up to this value if it is below it, to avoid extremely small threshold
             values.
+        maximum_threshold
+            The output threshold is rounded down to this value if it is above it, to avoid extremely large threshold
+            values.
         positions
             If input, these positions are used instead of the computed multiple image positions from the lens mass
             model.
@@ -380,6 +384,9 @@ def positions_likelihood_from(
             plane_redshift=plane_redshift,
         )
 
+        if maximum_threshold is not None:
+            threshold = min(threshold, maximum_threshold)
+
         return PositionsLH(
             positions=positions, threshold=threshold, plane_redshift=plane_redshift
         )