How to use multiple if else conditions when using "and" logic in a nested for-loop using python

Question

• I have a list of lists of lists
• The outer most list is the entire collection of members, each list within that is the individual members, and within that is each line of the raw text file I got split up into its individual elements.
• Each member's record has a Name line, indicated by the "NM1" label
• But not every member has an "End Date" field, indicated by the 'DTP' and '349' labels
• Likewise not every member has an "Prior ID" field, indicated by the 'REF' and '0F' labels
• I want to go through each record and if the field I need is there, extract the element of the list I need and append to a new list. If it isnt there, append a None value as a placeholder. I need each list to have the same number of values so when I put them as a pandas Series into a DataFrame, each series has the same length.

I got the data parsed into the format I want like this, as a simple example.

Groups = [[['NM1', 'IL', '1', 'SMITH', 'JOHN', 'PAUL', 'MR', 'JR', ''],
  ['REF', '1L', '690553677', ''],
  ['DTP', '348', 'D8', '20200601', ''],
  ['DTP', '349', 'D8', '20200630', '']],
 [['NM1', 'IL', '1', 'IMA', 'MEAN', 'TURD', 'MR', 'SR', ''],
  ['REF', '1L', '690545645', ''],
  ['REF', '0F', '001938383',''],
  ['DTP', '348', 'D8', '20200601', '']]]

I try using a for loop to go through each record and if the combination of those special "labels" exist in the group, append it to a new list with just the last element I want (the date, or the ID #). when I try to use multiple if- else conditions for each element I only get None values.

current_id = []
prior_id = []
start_date = []
end_date = []


for group in Groups:
    if ((line[0] == 'REF') and (line[1] == 'IL')) in (line for line in group):
        current_id.append(line[2])
    else:
        current_id.append(None)
    if ((line[0] == 'REF') and (line[1] == '0F')) in (line for line in group):
        prior_id.append(line[2])
    else:
        prior_id.append(None)
    if ((line[0] == 'DTP') and (line[1] == '348')) in (line for line in group):
        start_date.append(line[2])
    else:
        start_date.append(None)
    if ((line[0] == 'DTP') and (line[1] == '349')) in (line for line in group):
        end_date.append(line[2])
    else:
        end_date.append(None)

print(current_id)
print(prior_id)
print(start_date)
print(end_date)

[None, None]
[None, None]
[None, None]
[None, None]

It should be:

['690553677','690545645']
[None, '001938383']
['20200601', '20200601']
['20200630', None]

I know my logic must be off but how is the best way to do this?

Answer 1

You can use for and else statements, I defined a function called ids that will retrieve the ids:

Groups = [[['NM1', 'IL', '1', 'SMITH', 'JOHN', 'PAUL', 'MR', 'JR', ''],
           ['REF', '1L', '690553677', ''],
           ['DTP', '348', 'D8', '20200601', ''],
           ['DTP', '349', 'D8', '20200630', '']],
          [['NM1', 'IL', '1', 'IMA', 'MEAN', 'TURD', 'MR', 'SR', ''],
           ['REF', '1L', '690545645', ''],
           ['REF', '0F', '001938383',''],
           ['DTP', '348', 'D8', '20200601', '']]]

def ids(a, b):
    l = []
    for group in Groups:
        for lst in group:
            if lst[:2] == [a, b]:
                if lst[2] == 'D8':
                    l.append(lst[3])
                else:
                    l.append(lst[2])
                break
        else:
            l.append(None)
    return l
        
current_id = ids('REF', '1L')
prior_id = ids('REF', '0F')
start_date = ids('DTP', '348')
end_date = ids('DTP', '349')
        
print(current_id)
print(prior_id)
print(start_date)
print(end_date)

Output:

['690553677', '690545645']
[None, '001938383']
['20200601', '20200601']
['20200630', None]

Note the if statements I used: if lst[2] == 'D8':. I used that because I saw that not all of the list's id numbers are at index 2, some are at index 3.