8.18 LAB: Elements in a range

Question

Write a program that first gets a list of integers from input. That list is followed by two more integers representing lower and upper bounds of a range. Your program should output all integers from the list that are within that range (inclusive of the bounds).

Ex: If the input is:

25 51 0 200 33

0 50

the output is:

25,0,33,

The bounds are 0-50, so 51 and 200 are out of range and thus not output.

For coding simplicity, follow each output integer by a comma, even the last one. Do not end with newline.

Answer 1

Rutvik's code is a great concise solution, but there's some pretty complex stuff in there, so let's pick it apart and look at some alternatives as well.

## Get a list of integers from input

# Get the input

numbers = input("Enter a list of integers separated by spaces: ")

# The input comes in as a single string, so turn it into a list by splitting

# between every space. We now have a list of strings.

numbers = numbers.split()

# We still need to turn this into a list of integers.

integer_list = []

# There's quite a few ways to do this, but let's look at three.

# 1) This type of pattern will work in any language and gets at the main idea:

for number in numbers:

# We convert each string to an integer, and then add it to the list

integer_list.append(int(number))

# 2) Or we could use a list comprehension. This is my prefered method.

# This is essentially the same as above, just more concise.

integer_list = [int(n) for n in numbers]

# 3) Or we can use the map function as Rutvik did. Similar patterns are a bit more

# common in other languages such as Javascript or F#.

# Map takes two arguments: a function, and a list. That function is applied to

# each element of the list, and a "map" object is returned as the result.

# We take that map and convert it into a list.

num_list = list(map(int, numbers))

## Get the lower and upper bounds

upper_bound, lower_bound = [int(n) for n in input("Lower and upper bound: ").split()]

## Iterate through the list and output integers within the range

# Rutvik's answer here is great, though it should be pointed out that,

# while a <= b <= c works in python, the vast majority of languages will

# instead need to use something like (a <= b) and (b <= c)

for num in num_list:

if lower_bound <= num <= upper_bound:

print(num, end=',')

## Since we looked at map and list comprehensions earlier, we might also consider

# using filter and conditional list comprehensions

# Like map, filter takes a function and a list as its two arguments. The result is

# a filter with only the objects in the list that meet the criteria from the function.

def within_bounds(x):

return lower_bound <= x <= upper_bound

# We can also define this as a lambda function, which is common with map and filter

within_bounds_lambda = lambda x: lower_bound <= x <= upper_bound

filtered_numbers = list(filter(within_bounds, num_list))

# Or we could use a list comprehension.

filtered_numbers = [n for n in num_list if lower_bound <= n <= upper_bound]

# However we get the filtered list, we can just loop through and print it:

for n in filtered_numbers:

print(n, end=",")

# Though if we wanted to easily get rid of the final comma,

# we could do something like this:

# Using a comma between every item of a list, create a string from that list.

# Note that join() requires the elements of the list to also be strings

print(",".join(str(n) for n in filtered_numbers), end="")

Answer 2

# Get a list of integers from input

num_list = list(map(int, input().split()))

# Get the lower and upper bounds

lower_bound, upper_bound = map(int, input().split())

# Iterate through the list and output integers within the range

for num in num_list:

if lower_bound <= num <= upper_bound:

print(num, end=',')

This program first takes the list of integers as input and then takes the lower and upper bounds of the range. It iterates through the list and prints the integers that fall within the specified range, separated by commas.