for-loops and dictionaries

Asked Apr 06 '17 at 00:55

Active Apr 06 '17 at 01:53

Viewed 603 times

Trying to relearn python, working with Introducing Python by Bill Lubanovic. While learning about dictionaries, he uses this for loop to reverse the dictionary e2f to f2e:

e2f = {'dog': 'chien', 'cat': 'chat', 'walrus': 'morse'}
f2e = {}
for english, french in e2f.items():
    f2e[french] = english

I really don't understand these for loops, we never defined french or english, and I don't know how this process reverses the dictionary. If someone could explain this for loop it would be greatly appreciated!

edited Apr 06 '17 at 01:53

martineau

119,623
25
170
301

asked Apr 06 '17 at 00:55

Tmmcclelland

Did you try reading the [docs](https://docs.python.org/3.5/tutorial/controlflow.html#for-statements)? – juanpa.arrivillaga Apr 06 '17 at 00:59
1

If this book you're reading is using syntax without explaining it anywhere, you need to find a better book. – TigerhawkT3 Apr 06 '17 at 01:00
This was a specific case that I didn't understand in the book. I don't think that case was shown on the docs. – Tmmcclelland Apr 06 '17 at 01:02
When you do e2f.items(), it unpacks the dictionary and return a list: [('walrus', 'morse'), ('dog', 'chien'), ('cat', 'chat')] . The for loop is just looping through it and assigning the first value to english, and the second value to french. – Charles Tang Apr 06 '17 at 01:06
Okay, thank you very much! – Tmmcclelland Apr 06 '17 at 01:19

for-loops and dictionaries

0 Answers0