ProjectEuler#42 Coded triangle numbers

#The nth term of the sequence of triangle numbers is given by,
#tn = (n(n+1))/2; so the first ten triangle numbers are:

#1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

#By converting each letter in a word to a number corresponding to its
#alphabetical position and adding these values we form a word value.
#For example, the word value for SKY is 19 + 11 + 25 = 55 = t10.
#If the word value is a triangle number then we shall call the word
#a triangle word.

#Using words.txt (right click and 'Save Link/Target As...'), a 16K text
#file containing nearly two-thousand common English words,
#how many are triangle words?

#An integer x is triangular if and only if 8x + 1 is a square.
#Source: http://en.wikipedia.org/wiki/Triangular_number
#Section: Triangular roots and tests for triangular numbers

import string

def isPerfectSquare(n):
    if n < 0:
        return False
    result = int(n**0.5)
    return result*result == n

def isTriangle(n):
    return isPerfectSquare((8*n)+1)

def namesFile2List(fileName):
    namesHandle = open(fileName,'r')
    namesString = namesHandle.readline()
    namesHandle.close()
    namesListTemp = namesString.split(',')
    namesList = []
    for i in namesListTemp:
        namesList.append(i.strip('"'))
    return namesList

def createUCCoder():
    coderDict = {}
    upperCase = string.ascii_uppercase
    for i in range(len(upperCase)):
        coderDict[upperCase[i]] = i+1
    return coderDict

namesList = namesFile2List('words.txt')
coderDict = createUCCoder()

numOfTriWords = 0
for name in namesList:
    wordValue = 0
    for letter in name:
        wordValue += coderDict[letter]
    if isTriangle(wordValue):
        numOfTriWords += 1
print numOfTriWords