How to combine two sets of lists to a dictionary

Question

I have two sets of lists with similar data which I need to combine into a dictionary. The list must contain both sets of information filling in wherever the other has a "-". So far this is what I have..

aList = [['Last Name', 'First Name', '2000', '2012'], 
       ['Roberts', 'Gloria', '-', '123000'], 
       ['Arreguin', 'Jeffrey', '81000', '-'], 
       ['Myers', 'George', '-', '86000'], 
       ['Willis', 'Mabel', '112000', '-'], 
       ['Oneal', 'Kevin', '96000', '77000'], 
       ['Paz', 'Barbara', '-', '77000'], 
       ['Franklin', 'Claude', '94000', '-'], 
       ['Bradley', 'Shannon', '89000', '-'], 
       ['Fix', 'Anna', '76000', '126000'], 
       ['Meyer', 'Loretta', '-', '116000'], 
       ['Daniels', 'Christina', '85000', '-'], 
       ['Graham', 'Veronica', '-', '136000']]

newList = [['Last Name', 'First Name', '2000', '2012'], 
       ['Meyer', 'Loretta', '123000', '-'], 
       ['Arreguin', 'Jeffrey', '81000', '-'], 
       ['Mielke', 'George', '137000', '-'], 
       ['Thomas', 'Lewis', '132000', '-'], 
       ['Harper', 'Crystal', '80000', '-'], 
       ['Young', 'Gary', '-', '94000'], 
       ['Franklin', 'Claude', '94000', '-'], 
       ['Hedrick', 'James', '-', '105000'], 
       ['Bradley', 'Shannon', '89000', '-'], 
       ['Thigpen', 'Michael', '79000', '-'], 
       ['Willis', 'Mabel', '112000', '-'], 
       ['Hullinger', 'Molly', '70000', '-'], 
       ['Myers', 'George', '-', '86000'], 
       ['Paz', 'Barbara', '-', '77000'], 
       ['Edwards', 'Kathryn', '117000', '97000'], 
       ['Roberts', 'Gloria', '-', '123000'], 
       ['Daniels', 'Christina', '-', '137000'], 
       ['Graham', 'Veronica', '-', '136000']]

def mergeData(newList,aList):
    aDict={}
    for item in range(1,len(newList)):
        key=(newList[item][0],newList[item][1])
        value=(newList[item][2],newList[item][3])
        aDict[key]=value

    for item in range(1,len(aList)):
        #stuck here not sure if im going right way with this 


print(aDict)

Here's a sample

newList= ['Meyer', 'Loretta', '123000', '-']
aList=['Meyer', 'Loretta', '-', '116000']

so the combined dictionary should be

{(‘Meyer’, ‘Loretta’): (‘123000’,’116000’)}

for this entry.

Answer 1

Just loop over the first list to build a dictionary with a dict comprehension:

aDict = {(e[0], e[1]): (e[2], e[3]) for e in aList[1:]}

Next loop over the other, with a helper function to pick one or the other based on the - values:

def pick(vals):
    return vals[1] if vals[0] == '-' else vals[0]

for e in newList:
    key = (e[0], e[1])
    existing = aDict.get(key, ('-', '-'))
    value = (e[2], e[3])
    aDict[key] = tuple(map(pick, zip(existing, value)))

For your first input that results in:

{('Arreguin', 'Jeffrey'): ('81000', '-'),
 ('Bradley', 'Shannon'): ('89000', '-'),
 ('Daniels', 'Christina'): ('85000', '137000'),
 ('Edwards', 'Kathryn'): ('117000', '97000'),
 ('Fix', 'Anna'): ('76000', '126000'),
 ('Franklin', 'Claude'): ('94000', '-'),
 ('Graham', 'Veronica'): ('-', '136000'),
 ('Harper', 'Crystal'): ('80000', '-'),
 ('Hedrick', 'James'): ('-', '105000'),
 ('Hullinger', 'Molly'): ('70000', '-'),
 ('Last Name', 'First Name'): ('2000', '2012'),
 ('Meyer', 'Loretta'): ('123000', '116000'),
 ('Mielke', 'George'): ('137000', '-'),
 ('Myers', 'George'): ('-', '86000'),
 ('Oneal', 'Kevin'): ('96000', '77000'),
 ('Paz', 'Barbara'): ('-', '77000'),
 ('Roberts', 'Gloria'): ('-', '123000'),
 ('Thigpen', 'Michael'): ('79000', '-'),
 ('Thomas', 'Lewis'): ('132000', '-'),
 ('Willis', 'Mabel'): ('112000', '-'),
 ('Young', 'Gary'): ('-', '94000')}

All put together again in your merge function:

def pick(vals):
    return vals[1] if vals[0] == '-' else vals[0]

def mergeData(newList, aList):
    aDict = {(e[0], e[1]): (e[2], e[3]) for e in aList[1:]}

    for e in newList:
        key = (e[0], e[1])
        existing = aDict.get(key, ('-', '-'))
        value = (e[2], e[3])
        aDict[key] = tuple(map(pick, zip(existing, value)))

    return aDict