SGDClassifier - Why do I need to use argmax instead of argmin to find the lowest threshold satisfying given precision?
Okay, I solved this myself.
precisions &gt;= 0.90 doesn't create an array with precision scores only above 90%, but it transforms this array to the array of Booleans, where precisions below 90% are turned to False and the others are True.
argmax, if there are multiple identical, maximum values (and True is max here) returns the first index of this occurrence.
I sometimes hate this book, why he just doesn't use method like &quot;array.first_equals(True)&quot;?