如何用元组列表中的百分比替换数字？

Question

I have a list with tuples and need to change values in the tuples by apply a simple % formula (sum all the integers and display the percentage in replacement of the original integer) the rest of the tuple is to remain the same. I am not sure how to extract the number and perform this in the tuple, just initial code so far..

def tupleCounts2Percents(inputList):
    lst = inputList
    lst[0] = (9) #example
    print lst 

inputList = [('CA',100),('NY',300),('AZ',200)]
tupleCounts2Percents(inputList)

the output I need is

[('CA',0.166),('NY',0.5),('AZ',0.333)]

Answer 1

def tupleCounts2Percents(inputList):
    total = sum(x[1] for x in inputList)
    return [(x[0], 1.*x[1]/total) for x in inputList]

Answer 2

If you want to change the list in-place, such that the change reflects in the list using which the function was called, then you can simply enumerate() over the list and create new tuples, example -

>>> def tupleCounts2Percents(inputList):
...     lst = inputList
...     tot = sum(x[1] for x in lst)
...     for i,x in enumerate(lst):
...         lst[i] = (x[0],(1.*x[1])/tot)
...     print lst
...
>>> inputList = [('CA',100),('NY',300),('AZ',200)]
>>> tupleCounts2Percents(inputList)
[('CA', 0.16666666666666666), ('NY', 0.5), ('AZ', 0.3333333333333333)]

A list comprehension method for this -

>>> def tupleCounts2Percents(inputList):
...     lst = inputList
...     tot = sum(x[1] for x in lst)
...     lst[:] = [(x[0],(1.*x[1])/tot) for x in lst]
...     print lst
...
>>> inputList = [('CA',100),('NY',300),('AZ',200)]
>>> tupleCounts2Percents(inputList)
[('CA', 0.16666666666666666), ('NY', 0.5), ('AZ', 0.3333333333333333)]

---

If you do not want the list to change inplace, then instead of lst[:] use lst , Example -

>>> def tupleCounts2Percents(inputList):
...     lst = inputList
...     tot = sum(x[1] for x in lst)
...     lst = [(x[0],(1.*x[1])/tot) for x in lst]
...     print lst
...
>>> inputList = [('CA',100),('NY',300),('AZ',200)]
>>> tupleCounts2Percents(inputList)
[('CA', 0.16666666666666666), ('NY', 0.5), ('AZ', 0.3333333333333333)]
>>> inputList
[('CA', 100), ('NY', 300), ('AZ', 200)]