Questions on Dictionaries and Lists

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#1
  1. Why the first for loop is working and not the second one? Whats the purpose of .items()?
    a. Working for Loop
    dict.items()
    dict.items()1112×120 4.21 KB
    ![dictError1|690x147]

b. Error for loop

dictError1
dictError11102×235 10.7 KB
![dictKeys|690x74]

#2 
 dict = {'a':1,'b':2}

for item in dict:
    print(item)
a
b
for item in dict:
    print(dict[item])
1
2
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#3

If you iterate through the results of the .items() method of a dictionary it returns each key: value pair as a series of tuples. So if you wanted to use both key and value it’s not uncommon to call .items() in order to loop through them.

Without this argument though it defaults to same style as .keys() which only iterates through the keys, not the values (the other typical view used is .values()).
Check the docs for the details-

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#4

So does that mean without dict.items() I cant print the key and value at the same time

#5

You can use the following if you wanted to print both the key and value without using .items().

d = {1: 'a', 2: 'b', 3: 'c'}

for x in d:
  print(x, d[x])

The above would result in the following.

1 a
2 b
3 c

This way you are simply printing the key, then the result of using that same key to access its corresponding value in d.

However, using .items() can make your code more clear and understandable. It’s faster and easier to tell that a key and its corresponding value are printed if, for example, you used print(key, value) rather than print(key, my_dict[key]). Using .items() also creates a pair of variables (key, value) that you can use to access key and values more easily, whether individually or paired.

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