def generateNGrams(sequence, n):
ngrams = []
for i in range(len(sequence) - n + 1):
ngrams.append(' '.join(tuple(sequence[i:i + n])))
#print(str(n)+"-Grams Generated\n")
#print(ngrams[:5])
return ngrams
def create_ngram(n, texts,test=False):
'''
input: list of sentence with word tokennize
'''
# Clean text and add pseudo start and end code
lst_text = []
for s in texts:
s = [''.join(c for c in w if c not in string.punctuation) for w in s] # Remove punctuation
s = [w.lower() for w in s if w] # Remove the empty strings
s = ['<s>',] * (3 - 1) + s + ['</s>',]
lst_text.extend(s)
# For training text, include unknown words
if not test:
low_counter = [w for w in Counter(lst_text).keys() if Counter(lst_text)[w] < 2]
for i, w in enumerate(lst_text):
if w in low_counter :
lst_text[i] = '<UNK>'
# Build ngram
ngrams = []
for i in range(len(lst_text) - n + 1):
ngram = tuple(lst_text)[i:i+n]
ngrams.append(ngram)
return ngrams
def ngramify(clean, n):
ngrams = []
for i in range(len(clean) - n + 1):
grams = []
for j in range(n):
grams.append(clean[i + j])
grams = tuple(grams)
ngrams.append(grams)
return ngrams
def get3Grams(payload_obj):
'''Divides a string into 3-grams
Example: input - payload: "<script>"
output- ["<sc","scr","cri","rip","ipt","pt>"]
'''
payload = str(payload_obj)
ngrams = []
for i in range(0, len(payload) - 3):
ngrams.append(payload[i:i + 3])
return ngrams
def get1Grams(payload_obj):
'''Divides a string into 1-grams
Example: input - payload: "<script>"
output- ["<","s","c","r","i","p","t",">"]
'''
payload = str(payload_obj)
ngrams = []
for i in range(0, len(payload) - 1):
ngrams.append(payload[i:i + 1])
return ngrams
def create_tfidf_vectors(dataframe): speeches = dataframe['concat_speeches'].tolist() ngrams = [] for unit in speeches: ngrams.append(compute_ngrams(unit, 2)) ngrams_to_add = pd.Series(ngrams) dataframe['ngrams'] = ngrams_to_add.values tfidf = [] for element in ngrams: tfidf.append(compute_tfidf(element, num_speeches, doc_freq)) tfidf_to_add = pd.Series(tfidf) dataframe['tfidf'] = tfidf_to_add.values return dataframe
def generate_ngrams(s, n):
# konverzija u mala slova
s = s.lower()
# zamena svih ne-alfanumeričkih znakova razmacima
# važno je uključiti specifična slova srpskog alfabeta poput ž, š i sličih
s = re.sub(r'[^a-zA-Z0-9ćčžšđ\s]', ' ', s)
# razbijanje rečenica na tokene, bez praznih tokena
tokens = [token for token in s.split(" ") if token != ""]
# prolaskom kroz ulazni niz se generišu n-gramovi
# potrebno je i nadovezati razbijene tokene
offset = 0
ngrams = []
while (offset <= len(tokens)):
length = offset % n + n
ngrams.append(tokens[offset:(offset + length)])
offset = offset + 1
if (offset + length == len(tokens) + 1):
break
return ngrams
def calc_n_grams(data_line, n):
ngrams = []
#create pos-tagged tokens
wrds = nltk.pos_tag(nltk.word_tokenize(data_line))
#punctuation we want to delete
del_tk = {'LS', 'SYM', 'SENT', '#', '$', '"', '``', '{', '}', '(', ')', ',', ';', '.', ':', '\'\''}
#go through and remove punctuation in tokens
pop_ind = []
#collect indexes to delete
for i in list(range(0,(len(wrds))-1)):
if wrds[i][1] in del_tk:
pop_ind.insert(0,i)
#pop the undesired punctuation off the list
for i in pop_ind:
del(wrds[i])
if (n <= len(wrds)):
#add start and end tokens
wrds.insert(0,("START","SENT_TOKEN"))
wrds.append(("START","SENT_TOKEN"))
for i in list(range(0,(len(wrds)-n+1))):
ng = ()
for j in list(range(0,n)):
temp = tuple(wrds[i+j])
ng = ng + temp
ngrams.append(ng)
return ngrams
def generateNGrams(sequence, n):
ngrams = []
for i in range(len(sequence) - n + 1):
ngrams.append(' '.join(tuple(sequence[i:i + n])))
return ngrams
def freq_pval_finder(X, vectorizer, gram, alternative):
X_df = pd.DataFrame(X)
zeros =[]
ones = []
for i in X_df:
counter = 0
# print(X_df[i].shape)
# break
zero_filter = []
ones_filter = []
while counter < X_df[i].shape[0]:
# print(counter)
if X_df[i][counter] == 1:
ones_filter.append(counter)
if X_df[i][counter] == 0:
zero_filter.append(counter)
# print(counter)
# counter = 0
# while counter < i[0]:
counter += 1
zeros.append(zero_filter)
ones.append(ones_filter)
success = [] # word is present
failure = [] # word is absent
for i, j in zip(ones, zeros):
each_success = []
each_failure = []
for k in i:
each_success.append(Y_transpose[0][k])
for l in j:
each_failure.append(Y_transpose[0][l])
success.append(each_success)
failure.append(each_failure)
success_prop = []
failure_prop = []
for i,j in zip(success, failure):
success_prop.append(sum(i)/ len(i)) #gives the proportion of spams when the word is present
failure_prop.append(sum(j)/len(j)) #gives the proportion of spams when the word is not present
P_VAL = []
for i, j in zip(success, failure_prop):
p_val = binom_test(sum(i), len(i), j, alternative = alternative)
P_VAL.append(p_val)
word_keys = sorted(vectorizer.vocabulary_.items(), key = lambda x : x[1])
def word_to_ngrams(words, n):
return [' '.join(words[i: i + n]) for i in range(len(words) - n + 1)]
tokens = [nltk.word_tokenize(i) for i in corpus]
ngrams = []
for i in tokens:
ngrams.append(word_to_ngrams(i, gram))
word_to_grams = list(chain(*ngrams))
fdist = nltk.FreqDist(word_to_grams)
pval = []
c = 0
while c < len(P_VAL):
pval.append((word_keys[c][0], P_VAL[c]))
c += 1
sorted_pval = sorted(pval, key= lambda x: x[1])
word_freq_pval = []
excluded_words = []
for i in sorted_pval:
flag = 0
for j in fdist.most_common(1000):
if i[0] == j[0]:
word_freq_pval.append((i[0], i[1], j[1]))
flag = 1
if flag == 0:
excluded_words.append((i[0], i[1]))
for i in excluded_words:
word_freq_pval.append((i[0], i[1],fdist[i[0]]))
word_freq_pval = sorted(word_freq_pval, key = lambda x: x[1])
filtered_freq_pval = []
for i in word_freq_pval:
if i[1] <= 0.02 or i[1] >= 0.8:
filtered_freq_pval.append(i)
df_filtered_freq_pval = pd.DataFrame(filtered_freq_pval, columns= ['Words', 'P-Value', 'Frequency'])
return df_filtered_freq_pval
