create one dict from list of dicts in DataFrame

Question

I'm struggling with simple lambda to convert list of nested dicts stored in df column but got stuck.

My df looks like

index   synthkey    celldata
0   870322681ffffff [{'3400_251': {'s': -77, 'q': -8}}, {'3400_426': {'s': -116, 'q': -16}}]
0   87032268effffff [{'3400_376': {'s': -97, 'q': -12}}, {'3400_426': {'s': -88, 'q': -12}}]

What I'd like to achieve is to have it like that:

index   synthkey    celldata
0   870322681ffffff {'3400_251': {'s': -77, 'q': -8},'3400_426': {'s': -116, 'q': -16}}

I've tried multiple attempts like:

df['dicts'] = df['celldata'].apply(lambda x: {}.update(*x))

or

df['dicts'] = df.apply(lambda x: {*x['celldata']})

but it got me nowhere near the solution.

Thanks!

score 4 · Accepted Answer · answered May 14 '20 at 13:19

4

Let us try ChainMap

from collections import ChainMap
df['dicts']=df['celldata'].map(lambda x : dict(ChainMap(*x)))

answered May 14 '20 at 13:19

BENY

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Looks like it's working!, but what kind of black magic it is and why I've never heard of ChainMap :) – morf May 14 '20 at 13:25
@morf aha ~ https://stackoverflow.com/questions/23392976/what-is-the-purpose-of-collections-chainmap – BENY May 14 '20 at 13:27
@YORBEN_S thanks, it seems to be simplest approach. It's a pitty I haven't heard of ChainMap before. My bad! – morf May 14 '20 at 13:36

score 0 · Answer 2 · answered May 14 '20 at 13:32

Using a simple for-loop to merge the dictionaries using merge_dict = {**dict_one, **dict_two}.

df = pd.DataFrame([{
    'index': 0,
    'synthkey': '870322681ffffff',
    'celldata': [{'3400_251': {'s': -77, 'q': -8}}, {'3400_426': {'s': -116, 'q': -16}}]
},{
    'index': 0,
    'synthkey': '87032268effffff',
    'celldata': [{'3400_376': {'s': -97, 'q': -12}}, {'3400_426': {'s': -88, 'q': -12}}]
}])

def merge_dicts(list_of_dicts):
    out = {}
    for elem in list_of_dicts:
        out = {**out, **elem}
    return out

df['new'] = df['celldata'].apply(merge_dicts)
print(df.head())
#    index         synthkey                                           celldata  \
# 0      0  870322681ffffff  [{'3400_251': {'s': -77, 'q': -8}}, {'3400_426...   
# 1      0  87032268effffff  [{'3400_376': {'s': -97, 'q': -12}}, {'3400_42...   

#                                                  new  
# 0  {'3400_251': {'s': -77, 'q': -8}, '3400_426': ...  
# 1  {'3400_376': {'s': -97, 'q': -12}, '3400_426':...

create one dict from list of dicts in DataFrame

2 Answers2