def twoGramFrequencyCount(tokens : [str]) -> [Frequency]:
'''
Counts frequency of 2grams from a tokenized list.
'''
if not tokens: #check if list is empty, [] == False
return []
tokens = list(filter(lambda x: x !='', tokens)) #filters out empty strings
tempFreq = defaultdict(int)
for twoGram in zip(tokens,tokens[1:]): # for (token,token) in [(token,token)]
'''
iterate over a list of the combined list of words and the off-set list of words to create the twoGrams,
using a defaultdict(int) with the 2gram as key and count duplicates for value
'''
tempFreq[' '.join(list(twoGram))] += 1 # tempFreq['token token'] = frequency value
return Utilities.collateFrequencies(tempFreq)
def palindromeFrequencyCount(tokens : [str]) -> [Frequency]:
'''
Counts the frequency of palindromes in a given list of tokens
'''
if not tokens: #check if list is empty, [] == False
return []
tempFreq = defaultdict(int)
palindromeAccumulator = '' '' #The variable accumulates tokens into a string until a palindrome is form
tokens.append('addOne') #For the algorithm to work it is necessary that the last token ends a palindrome
for i in range(len(tokens)):
'''
iterates for the length of the tokens list. Each iteration checks palindromAccumulator and the reverse of palindrome accumulator twice.
if checks for non-matches and catches the empty string(entry case). When true, appends token[i] to palindromeAccumulator
else there is a palindrome. tempFreq is incremented and palindromeAccumulator is reset to token[i]
'''
if palindromeAccumulator != palindromeAccumulator[::-1] or palindromeAccumulator == '': # compare pal and revesed pal; check for pal
palindromeAccumulator += tokens[i] #concatenate tokens[i] to palindromeAccumulator
else:
tempFreq[palindromeAccumulator] += 1 # assign value to dict
palindromeAccumulator = tokens[i] #reset to palindromeAccumulator to tokens[i]
return Utilities.collateFrequencies(tempFreq)
