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Dale Potter
1,756 PointsFunctional Python Challenge: Map and Filter Comprehension
Hello,
I'm a bit confused about what this question is asking - I’ve just added the three iterations of this code and I am not passing the challenge. Have I misinterpreted the question?
Here’s the code, with three solutions at the bottom
Many thanks, Dale
Challenge Task 1 of 1
As a dumb American, I don't understand Celsius temperatures. Using c_to_f and a list comprehension, create a variable named good_temps. Convert each Celsius temperature into Fahrenheit, but only if the Celsius temperature is between 9 and 32.6.
temperatures = [
37,
0,
25,
100,
13.2,
29.9,
18.6,
32.8
]
def c_to_f(temp):
"""Returns Celsius temperature as Fahrenheit"""
return temp * (9/5) + 32
def is_good_temp(temp_c):
"""Returns True if temp_c is between 9 and 32.6 degrees"""
return (temp_c >= 9) and (temp_c <= 32.6)
# good_temps = filter(is_good_temp, map(c_to_f, temperatures))
# Bummer, did you use a list comprehension?
# good_temps = [temp_c for temp_c in filter(is_good_temp, map(c_to_f, temperatures))] # Bummer, did you use a list comprehension?
# good_temps = filter(is_good_temp, [temp_c for temp_c in map(c_to_f, temperatures)]) # Bummer, did you use a list comprehension?
good_temps = [x for x in map(c_to_f, temperatures) if is_good_temp(x) ]
# Got some wrong values in good_temps
1 Answer
Chris Freeman
Treehouse Moderator 68,468 PointsYou don't need map to solve the first Task in this challenge:
good_temps = [c_to_f(temp) for temp in temperatures if temp > 9 and temp < 32.6]
Update: I was able to modify your code to pass the challenge. It issue is is_good_temp is comparing to target Celsius numbers, but the map has already converted the numbers to Fahrenheit. Here is a version of your code that passes. I didn't use your is_good_temp since it wasn't part of the challenge.
# Original
good_temps = [x for x in map(c_to_f, temperatures) if X > 9 and x < 32.6 ]
# Passing version
good_temps = [x for x in list(map(c_to_f, temperatures)) if x > c_to_f(9) and x < c_to_f(32.6)]
Nathan Tallack
22,164 PointsNathan Tallack
22,164 PointsWow. I was wracking my brain trying to see that. You've been doing this too long Chris. ;)
Dale Potter
1,756 PointsDale Potter
1,756 PointsThanks a lot Chris
Tobias Edwards
14,458 PointsTobias Edwards
14,458 Points"...but only if the Celsius temperature is between 9 and 32.6."
The question specifies the Celsius temperature, so why would you need to pass the '9' and '32.6' into the 'c_to_f' function? Because doesn't this convert the '9' and '32.6' into Fahrenheit values, so we're then checking against Fahrenheit values, not Celsius ones as specified in the question?
Chris Freeman
Treehouse Moderator 68,468 PointsChris Freeman
Treehouse Moderator 68,468 PointsTobias Edwards: Yes. The second solution is awkward. It is not a recommended solution, but rather shows a way the OP code might work. Since the OP solution maps all of the temperatures using
c_to_fbefore limiting to the target range, the source list is already all Fahrenheit values. Therefore, to get the range check to work post-conversion, the range values must also be converted to Fahrenheit. The end result is the same, but this method is less efficient since it converts more values to Fahrenheit than necessary compared to limiting on the Celsius number range then converting to Fahrenheit.