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pythonlistgeneratorarcpy

Assign differing values to list generator results


I am using list generators as shown below. I would like to know how I can assign different text or values to the individual list generators. In the sample code, I can only assign values for all the list generators at once. For example, I would like to assign for v, row1[3]="value 1", for k,row1[3]="value 2" and for m, row1[3]="value 3". How can I acheive that?

v = (item for item in propadd if item[0]==row1[8] and harversine(custx,custy,item[2],item[3])<1500)
k = (item for item in custadd if item[0]==row1[4])
m = (item for item in numlist if re.search(r"^[0-9]+(?=\s)",row1[0]) is not None and item[0]==re.search(r"^[0-9]+(?=\s)",row1[0]).group())
for gen in (v, k, m):
    l = list(gen) 
    if len(l) == 1:
        row1[1] = l[0][1]
        row1[2] = l[0][2]
        break

Solution

  • There are a couple of different ways of assigning additional values to the different generators. The easiest would be to have a dictionary keyed by the generator or an iterable of the same length containing the values. Both approaches are shown here:

    Iterable

    v = (item for item in propadd if item[0]==row1[8] and harversine(custx,custy,item[2],item[3])<1500)
    k = (item for item in custadd if item[0]==row1[4])
    m = (item for item in numlist if re.search(r"^[0-9]+(?=\s)",row1[0]) is not None and item[0]==re.search(r"^[0-9]+(?=\s)",row1[0]).group())
    extraValues = ('value 1', 'value 2', 'value3')
    for ind, gen in enumerate((v, k, m)):
        l = list(gen) 
        if len(l) == 1:
            row1[1] = l[0][1]
            row1[2] = l[0][2]
            row1[3] = extraValues[ind]
            break
    

    Dictionary

    v = (item for item in propadd if item[0]==row1[8] and harversine(custx,custy,item[2],item[3])<1500)
    k = (item for item in custadd if item[0]==row1[4])
    m = (item for item in numlist if re.search(r"^[0-9]+(?=\s)",row1[0]) is not None and item[0]==re.search(r"^[0-9]+(?=\s)",row1[0]).group())
    extraValues = {v: 'value 1',
                   k: 'value 2',
                   m: 'value3')
    for gen in (v, k, m):
        l = list(gen) 
        if len(l) == 1:
            row1[1] = l[0][1]
            row1[2] = l[0][2]
            row1[3] = extraValues[gen]
            break
    

    You could also have some complex scenario where the extra value could be generated by some function other than a dictionary lookup or tuple index.