sorted(x) modifies the argument x (bug?)

x.sort() modifies x, but sorted(x) doesn't modify the argument x in Python as following:

>>> l=[2,1,3]
>>> sorted(l)
[1, 2, 3]
>>> l
[2, 1, 3]

But, I encountered a Transcrypted code modifying the argument x in sorted(x):

print('cups.x= ', [c.mesh.position.x for c in cups])
cupClosest= sorted(cups, key=lambda cup: cup.mesh.position.subtract(posLocal).length())[0]
print('cups.x(after sorted())= ', [c.mesh.position.x for c in cups])

result:

cups.x=  [-0.779135848130025, -0.259711949376675, 0.259711949376675, 0.779135848130025]
cups.x(after sorted())=  [0.259711949376675, -0.259711949376675, 0.779135848130025, -0.779135848130025]

Based on the example above, it looks like sorted(x) modifies x as x.sort() in Transcrypt. It is not true in Python.

The sorted() method call the copy() method
And the copy() method contains :

export function copy (anObject) {
    if (anObject == null || typeof anObject == "object") {
        return anObject;
    } else {
        var result = {};
        for (var attrib in obj) {
            if (anObject.hasOwnProperty (attrib)) {
                result [attrib] = anObject [attrib];
            }
        }
        return result;
    }
}

It's bugged
If it's an object (an array in your case) it return the object. So useless for a copy method.
Otherwise an error occur because "obj" is not know in the loop

The copy method must be something like :

export function copy (anObject) {
    if (anObject == null || typeof anObject != "object") {
        return anObject;
    }
    else {
        if (anObject instanceof Array){
          var res = []
          for(var elem of anObject){
            res.push(elem)
          }
          return res
        }else{
          var result = {};
          for (var attrib in anObject) {
            if (anObject.hasOwnProperty (attrib)) {
              result [attrib] = anObject [attrib];
            }
          }
          return result;
        }
    }
}

The copy function that sorted is using has been re-implemented as part of the new copy module in dev_3.9.3 branch to be released in v3.9.3
It should work in most cases, but needs a bit more testing.

Merged to master on PR #876

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sorted(x) modifies the argument x (bug?) #866

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sorted(x) modifies the argument x (bug?) #866

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Iv3li0s commented on May 3, 2024

JennaSys commented on Jul 6, 2024

JennaSys commented on Jul 17, 2024

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