Python: How to deep copy a list of dictionaries

Question

I have a list whose each element is a dictionary. Each element looks something like this

{'CELL': <Cell SOW16007.2.AC7>, 'COUNT': 2, 'NAMELIST': [], 'NAME': u'', 'LEVEL': u'SSE'}

I need to make a backup of this list.Normal assignment or using shallow copy is not option i can use as i will making changes to the original. But when i use deepcopy backUpNames=deepcopy(oldNames) I'm getting an error :

TypeError: unhashable type: 'array.array'

What wrong am i doing here? How can i solve this?

This is a not a duplicate question as I have already used deepcopy, problem i am facing is with the error deepcopy is throwing.

Minimal Code:

Using openpxl i iterate the sheet and append the values to a list

wb=openpyxl.load_workbook(sys.argv[3],data_only=True)
_ts=wb.active 
oldNames.append({'NAME':_ts['G7'].value,'LEVEL':_ts['H7'].value,'CELL':_ts['F7'],'COUNT':0,'NAMELIST':[]})
backUpNames=deepcopy(oldNames)#error occurring here

Thank You

@MoinuddinQuadri - That's not a duplicate at all. OP is using `copy.deepcopy` already, and getting an error. — TigerhawkT3, Dec 16 '16 at 06:22
From given error, I can assume that `Cell` is some complex type that doesn't support hashing. Can You confirm by trying this: `from collections import Hashable; isinstance(d['CELL'], Hashable)`? — Fejs, Dec 16 '16 at 06:35
Possible duplicate of [Deep copy a list in Python](http://stackoverflow.com/questions/17873384/deep-copy-a-list-in-python) — Netwave, Dec 16 '16 at 08:46

score 2 · Answer 1 · edited Dec 16 '16 at 08:44

2

import copy
list = [{'a':1,'b':2},{'c':3,'d':4}]
cpy_list = []
for li in list:
    d2 = copy.deepcopy(li)
    cpy_list.append(d2)
print cpy_list

edited Dec 16 '16 at 08:44

Jordfräs

8,903
3
27
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answered Dec 16 '16 at 06:57

dsingh

29
3

1

What's the point here? OP said he knows how to use `deepcopy`, he have a specific problem, for which this doesn't help a bit. – Fejs Dec 16 '16 at 07:01
1

I still get the same error TypeError: unhashable type: 'array.array'. – Vinod Pn Dec 16 '16 at 07:06

score 1 · Answer 2 · answered Dec 16 '16 at 07:12

I think that this will fix the problem:

oldNames.append({'NAME':_ts['G7'].value,'LEVEL':_ts['H7'].value,'CELL':_ts['F7'].value,'COUNT':0,'NAMELIST':[]})

Note this key/value pair: 'CELL':_ts['F7'].value

I suppose that You can't use cell as object here, but rather only it's value.

Python: How to deep copy a list of dictionaries

2 Answers2