I’m trying to delete elements from _notes that have _type as 1, but i keep getting an error and I’m not sure what it means, nor do I know how to fix it.. can anyone help me?
My trimmed JSON:
{ "_notes": [ { "_time": 10, "_lineIndex": 2, "_lineLayer": 0, "_type": 0, "_cutDirection": 7 }, { "_time": 12, "_lineIndex": 2, "_lineLayer": 0, "_type": 1, "_cutDirection": 1 }, { "_time": 14, "_lineIndex": 2, "_lineLayer": 1, "_type": 1, "_cutDirection": 0 } ] }
My python script:
#!/usr/bin/python3 import json obj = json.load(open("ExpertPlusStandardd.dat")) for i in range(len(obj["_notes"])): print(obj["_notes"][i]["_type"]) if obj["_notes"][i]["_type"] == 1: obj.pop(obj["_notes"][i]) open("test.dat", "w").write( json.dumps(obj, indent=4, separators=(',', ': ')) )
Error:
Traceback (most recent call last): File "C:programmingpythontrain_one_handrun.py", line 9, in <module> obj.pop(obj["_notes"][i]) TypeError: unhashable type: 'dict'
Advertisement
Answer
It is usually a bad idea to delete from a list that you’re iterating. Reverse iterating avoids some of the pitfalls, but it is much more difficult to follow code that does that, so usually you’re better off using a list comprehension or filter.
obj["_notes"] = [x for x in obj["_notes"] if x["_type"] != 1]
This gives us the expected output :
{'_notes': [ { '_time': 10, '_lineIndex': 2, '_lineLayer': 0, '_type': 0, '_cutDirection': 7 } ] }