难以理解列表理解

Question

I need to use a list comprehension to convert certain items in a list from Celsius to Fahrenheit. I have a list of temperatures. What my best guess is at this point looks like this:

good_temps = [c_to_f(temp) for temp in temperatures if 9 < temperatures[temp] <32.6]

However I'm not doing something right and I can't figure it out.

Answer 1

An alternative solution to the one pointed in another answer is to use filter to get the subset:

filter(lambda temp: 9 < temp < 32.6, temperatures)

Then a list comprehension to make the transformations:

[c_to_f(temp) for temp in temperatures] 

Final expression:

good_temps = [c_to_f(temp) for temp in filter(lambda t: 9 < t < 32.6, temperatures)]

Answer 2

You're very close. What you need is:

good_temps = [c_to_f(temp) for temp in temperatures if 9 < temp < 32.6]

This code will only convert temp if it's greater than 9 and less than 32.6. For temp values outside that range nothing will get added to good_temps .

temp is already an item from temperatures , so temperatures[temp] doesn't make much sense, since that's attempting to use an item of temperatures as an index.