Lists and Strings

For the Lists exercises

Exercise 7

def count_odd(lst):
    #takes input of list
    # make a counting variable
    odd_count = 0
    #wrap if in a for loop
    for number in lst:
        # Is it odd?
        if number % 2 == 1:
            odd_count += 1
    return odd_count

print(count_odd([5,1,3]))

Output 3

Exercise 8

def even_sum(list):
    sum_even = 0
    for number in list:
        if number % 2 == 0:
            sum_even += number
    return sum_even

print(even_sum([2,3,4,5]))

Ouput 6

Exercise 9

def neg_sum(list):
    sum_neg = 0
    for number in list:
        if number < 0:
            sum_neg += number
    return sum_neg

print(neg_sum([-3,-5,5,]))

Output

-8

Exercise 14

I couldn't get this one to work, but here is my attempt

def old_scen(list):
    scen_old=old
    for str in list:
        if str = 'old'
        replace = 'new'
print('old shoes')

For the strings exercises, I had some trouble.

With number 6, I modified the code which was the answer for number 7 and I thought it would work but it doesn't.

from test import testEqual

def reverse(astring):
    reversed = ' '
    for char in astring:
        reversed = char
    return reverse

testEqual(reverse("happy"), "yppah")
testEqual(reverse("Python"), "nohtyP")
testEqual(reverse("shoe"),"eohs")

The output looks like this

Test Failed: expected yppah but got <function reverse>
Test Failed: expected nohtyP but got <function reverse>
Test Failed: expected eohs but got <function reverse>

For exercise 7 I was able to get it because they give you the answer ``` from test import testEqual

def reverse(mystr): reversed = '' for char in mystr: reversed = char + reversed return reversed

def mirror(mystr): return mystr + reverse(mystr)

testEqual(mirror('good'),'gooddoog') testEqual(mirror('Python'),'PythonnohtyP') testEqual(mirror(''), '') testEqual(mirror('a'),'aa') ```

The output looks like this Pass Pass Pass Pass

11 I could get because they give you the answer. Here is what they got. I don't quite understand it. I think I will have to reread the strings chapter.

from test import testEqual

def remove(substr,theStr):
    index = theStr.index(substr)
    if index < 0: # substr doesn't exist in theStr
        return theStr
    return_str = theStr[:index] + theStr[index+len(substr):]
    return return_str

testEqual(remove('an', 'banana'),'bana')
testEqual(remove('cyc', 'bicycle'), 'bile')
testEqual(remove('iss', 'Mississippi'), 'Missippi')
testEqual(remove('egg', 'bicycle'), 'bicycle')

The output is pass pass pass pass

For 12 I tried to modify the answer from 11 but couldn't get it to work. I put in this

from test import testEqual

def remove_all(substr,theStr):
    index = theStr.index(substr)
    if index < 0: # substr doesn't exist in theStr
        return theStr
    return_str = theStr[index+len(substr):]
    return return_str

testEqual(remove_all('an', 'banana'), 'ba')
testEqual(remove_all('cyc', 'bicycle'), 'bile')
testEqual(remove_all('iss', 'Mississippi'), 'Mippi')
testEqual(remove_all('eggs', 'bicycle'), 'bicycle')

I got this ```

Test Failed: expected ba but got ana Test Failed: expected bile but got le Test Failed: expected Mippi but got issippi ```

As you can see I am having a hard time with the strings.

SILShack Spring 2014

Lists and Strings