IndexError: Python list index out of range - list

Question

I have an empty list, (r) and declared first element as r[0] = a
import time, urllib.request,random
def getDictionary():
word_site = "http://svnweb.freebsd.org/csrg/share/dict/words?view=co&content-type=text/plain"
response = urllib.request.urlopen(word_site)
txt = response.read()
return txt.splitlines()
def getWordsList(listOfWords, sample):
word = ""
randWords = []
for i in range(0,sample):
while(len(word) <=2):
word = random.choice(listOfWords).decode('utf-8')
randWords.append(word)
word = ""
return randWords
start = True
noOfWords = 25
words = getDictionary()
wordsList = getWordsList(words, noOfWords)
start = True
print ("\nINSTRUCTIONS\nWhen the coundown gets to zero, type the word in lowercase letters!\n That's the only rule!")
name = input("What is your name? ")
name = name.split(" ")
input("Press enter when ready...")
while start == True:
print("Game will start in: ")
print ("3 seconds")
time.sleep(1)
print ("2 seconds")
time.sleep(1)
print ("1 seconds")
time.sleep(1)
times = []
k = list()
r = list()
for i in range(25):
startTime = time.time()
userWord = input(str(i+1) + ". " + wordsList[i].capitalize() + " " )
k.append(wordsList[i].capitalize())
if (userWord.lower() == wordsList[i].lower()):
endTime = time.time()
times.append(endTime - startTime)
r[i] = str(endTime - startTime)
else:
times.append("Wrong Word")
r[i] = ("Wrong Word")
Above is where I am having a problem.
for i in range(25):
startTime = time.time()
print (str(i+1) + ". " + str(k[i]) + ": " + str(times[i]) )
a = 0
for i in range(25):
a = a+i
for i in range(25):
if r[i] == "Wrong Word":
r = r.pop(i)
b = (a/len(r))
c = round(b, 2)
print (c)
start = False
here is my error:
r[i] = "Wrong Word"
IndexError: list assignment index out of range

Answer 1

The pop() method removes an element from the list and returnes it (see an example). What I think is happening is that at some point the condition of the if statment resolves to true. Next, after calling r.pop(i) r is replaced by its i-th element. It's probpably a string so calling its (i+1)-th element later can result in Index out of range error.
In other words, something like this is happening:
r = ["a", "foo", "bar", "baz"]
for i in range(4):
if r[i] == "a": # for i=0 this gives "a" == "a"
r = r.pop(i) # later,this results in r = "a"
next loop iteration with i = 1 will result in "a"[1] which will result in Index out of range.
All in all instead of:
for i in range(25):
if r[i] == "Wrong Word":
r = r.pop(i)
you could just write:
r = [item for item in r if item != "Wrong word"]
which would be also more pythonic solution.