Access dict keys and list elements by same index to loop over and assign values

Question

I have more than 15 dataframes and one list. Given the sample below

unit_list = ['%','umol/l','mmol/l','mmol/l','g/dL','mmol/l','umol/l','','mg/mmol','mg/L','','mg/mmol','g/L'
        'g/day','','mg/L','','mg/day','','mmol/l','','cells/uL','','','cells/uL']

#TWO DATAFRAME for sample

dataframesdict[hbA1c] = pd.DataFrame({'person_id':[1,2,3],'Date': ['2009-01-05 00:00:00','2009-01-05 00:00:00','2013-01-31 00:00:00'],'Value': [9.6,9.6,10]})
dataframesdict[Creatinine]   = pd.DataFrame({'person_id':[1,2,3],'Date': ['2119-01-05 00:00:00','2129-01-05 00:00:00','2113-01-31 00:00:00'],'Value': [19.6,29.6,210]})

What I would like to do is create a new column called unit in each dataframe present under the dataframesdict and fill the value from unit_list

I have got the unit_list ordered, so its like 0th element from unit_list should be filled in as value for unit column under 0th key (0th dataframe) in dataframesdict

Similarly dataframesdict[1]['unit] = unit_list[1]

I tried the below but it doesn't work due to the use of Index as key.

for i in range(len(key_list)):
    dataFramesDict[i]['unit'] = unit_list[i]

How can I make use of index to access and assign values at the same time? Below screenshot shows the expected output. Hba1c is the first index item in dict, so the corresponding first index item from unit_list is filled in as value in 'unit' column of the dataframe

score 1 · Answer 1 · answered Jul 31 '19 at 04:36

1

To start with, unless you are on python 3.6=>, dict will not guarantee you the order. In order words, hdA1c will not always be the first key.

If you were to maintain the order, use collections.OrderedDict.

As for the actual problem, enumerate would do the job:

for i, (k, v) in enumerate(dataframesdict.items()):
    v['unit'] = unit_list[i]

print(dataframesdict['hbA1c'])

Output:

                  Date  Value  person_id unit
0  2009-01-05 00:00:00    9.6          1    %
1  2009-01-05 00:00:00    9.6          2    %
2  2013-01-31 00:00:00   10.0          3    %

answered Jul 31 '19 at 04:36

Chris

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I am using Python 3.7.1. So will that retain the dict order? – The Great Jul 31 '19 at 04:40
@ALVES yes it should. I wasn't sure because the tag included `python-2.7` :P – Chris Jul 31 '19 at 04:40
Your answer is better as it applies across all version of Python. Will mark as a silution after the time limit is over – The Great Jul 31 '19 at 04:41
Can you help me with this post? https://stackoverflow.com/questions/57285680/dont-drop-all-nas-during-stack-operation-in-python – The Great Jul 31 '19 at 07:51

score 0 · Accepted Answer · answered Jul 31 '19 at 04:35

I am using Python 3.7.1 (it retains dict order) and the below answer works.However I welcome any better and efficient answer and looking forward to it

for i in range(len(key_list)):
    a = list(dataFramesDict)[i]
    dataFramesDict[a]['unit'] = unit_list[i]

Access dict keys and list elements by same index to loop over and assign values

2 Answers2