如何在 Python 中比较元组元组中的元素

Question

I am new to python and I came across this exercise:

Given the following tuple of tuples, calculate the total number of apples, bananas, melons and pineapples comparing the first element of each tuple:

myTupleofTuples = (("apple",1),("banana",1),("apple",2),("melon",1),("pineapple",2),("banana",2))
for i,j in myTupleofTuples:
  counter = 0
  for k in range(len(myTupleofTuples)):
    if i in myTupleofTuples[k][0]:
      counter = counter + myTupleofTuples[k][1]
      print(i+" is in "  +myTupleofTuples[k][0]+ " the counter of " +i+ " is " ,counter )

I am used to work with java or c and somehow developed the previous solution, although I would like a more python like and elegant solution for the problem.

Answer 1

One of my favorite patterns for counting is by using a defaultdict. Like this:

from collections import defaultdict

myTupleofTuples = (("apple",1),("banana",1),("apple",2),("melon",1),("pineapple",2),("banana",2))
sums = defaultdict(int)
for fruit, count in myTupleofTuples:
    sums[fruit] += count
print(list(sums.items()))

Answer 2

Dictionary comes very handy when you are solving this problem. As a example here is the code below.

count_dict = {} # creating an empty dictionary
for fruit,num in myTupleofTuples: # loops each tuple and separate each individual tuple into fruit and num variable
  count = count_dict.get(fruit, 0) # get value if fruit exist in dictionary else give 0
  count_dict[fruit] = num + count # add the count with number

If you want to print them as you have:

for key,value in count_dict.items():
  print('{} is in {} and There are {} {}\n'.format(key, [x for x in range(len(myTupleofTuples)) if myTupleofTuples[x][0]==key] value, key)) 
  # just adding list comprehension for finding index, you can use function as well

Output:

apple is in [0, 2] and There are 3 apple
banana is in [1, 5] and There are 3 banana
melon is in [3] and There are 1 melon
pineapple is in [4] and There are 2 pineapple

Answer 3

A bit more Pythonic version (using f-strings and unpacking variables) equivalent to yours:

for fruit1, number1 in myTupleofTuples:
    counter = 0
    for fruit2, number2 in myTupleofTuples:
        if fruit1 in fruit2:
          counter += number2
          print(f"{fruit1} is in {fruit2} the counter of {fruit1} is {counter}")

I would have counted the fruits instead (same name, so by using == instead of in when comparing names), by using a Counter :

from collections import Counter
counter = Counter()
for name, value in myTupleofTuples:
    counter[name] += value

Answer 4

Another version:

my_tuple_of_tuples = (
    ("apple", 1),
    ("banana", 1),
    ("apple", 2),
    ("melon", 1),
    ("pineapple", 2),
    ("banana", 2)
)

quantities = (
    (this_fruit,
     sum(quantity
         for fruit, quantity in my_tuple_of_tuples
         if fruit == this_fruit))
    for this_fruit in {tuple_[0] for tuple_ in my_tuple_of_tuples}
)
print(*(f'{fruit}: {quantity}' for fruit, quantity in quantities))