import sys
from pdfminer.high_level import extract_pages
from pdfminer.layout import LTTextContainer, LTLine, LTChar
#this module contains one public method to parse the title of a typical PDF academic paper, given its filepath
#the parsing often fails because of difficulty in parsing PDF files
def getTitle(filepath):
"""main method to extract the title of a pdf file"""
try:
filepath = filepath.strip()
except TypeError:
print("filepath not a string")
if not filepath[len(filepath)-4:len(filepath)].lower() == ".pdf":
sys.exit("filepath not ending with .pdf in " + filepath)
try:
data = extractFirstPageElements(filepath)
texts = data[0]
fonts = data[1]
maxFontPos = extractTitlePos(fonts)
uncleanedTitle = extractTitle(texts, maxFontPos)
title = cleanTitle(uncleanedTitle)
except: #mostly due to IndexError as no texts are read in due to unreadable file or blank page, or some readTexts-fontSize mismatch
title = "Unknown"
if len(title) > 120: #ultra-long title likely error
title = "Unknown"
return title
def extractFirstPageElements(filepath):
"""helper method to extract text elements and their corresponding font sizes into lists"""
fonts = []
elements = []
for page in extract_pages(filepath):
for element in page:
if isinstance(element, LTTextContainer):
for text_line in element:
for character in text_line:
if isinstance(character, LTChar):
font_size = character.size
break #first character only, assuming others in text_line have the same size
fonts.append(font_size)
elements.append(element.get_text())
break #read first page only
return [elements, fonts]
def extractTitlePos(fonts):
"""helper method to extract the positions having the largest font size"""
font_pos = []
maxFont = max(fonts)
for pos, size in enumerate(fonts):
if size == maxFont:
font_pos.append(pos)
return font_pos
def extractTitle(elements, positions):
"""helper method to extract those elements having the largest font size, then return as a joint string"""
title = []
for i in positions:
title.append(elements[i])
return " ".join(title)
def cleanTitle(title):
"""helper method to clean the title by removing \n and illegal filename symbols"""
englishArticles = ("a", "an", "the") #to remove if start word of title
title = title.strip() #remove whitespaces
title = title.replace("\n", " ") #remove any inline \n
title = title.replace(":", " -") #replace invalid file : symbol
title = title.replace("?", " ") #replace invalid file ? symbol
title = title.replace("*", "") #replace invalid symbol
title = title.replace("@", "") #replace invalid symbol
title = title.replace("/", " ") #replace invalid symbol
title = title.replace(" ", " ") #remove potential double whitespaces
title = title.title() #capitalize each word
#remove starting article if one
firstWord = title.split()[0].lower() #first word of title
if firstWord in englishArticles:
secondWord = title.split()[1] #second word of title
secondWordPos = title.index(secondWord) #where second word starts
title = title[secondWordPos:] #remove the starting article off title
#perform word capitalization, some keywords should be in all lower-case or upper-case, regular words are letter-capitalized
words = title.split() #individual words in the title, each letter-capitalized
#var to hold words that should be all lower-case
lowercaseWords = ("a", "an", "the", "at", "to", "from", "for", "using", "of", "among", "across", "during","what", "with", "and", "or", "between", "in", "on", "is", "are", "as", "there", "under", "toward", "towards", "through", "via", "by", "based", "vs", "versus", "its", "it", "their")
#var to hold words that should be all upper-case
uppercaseWords = ("us", "usa", "eu", "uk", "hk", "nyse", "ftse", "hkse", "pca", "etf", "etfs", "fx", "ipo", "hft", "spx", "vix", "vxx", "adr", "adrs")
capAdjustedWords = [] #var to hold capitalization-appropriate words
for word in words: #check each word one by one
if word.lower() in lowercaseWords:
capAdjustedWords.append(word.lower()) #capitalize to lower-case
elif word.lower() in uppercaseWords:
capAdjustedWords.append(word.upper()) #capitalize to upper-case
else:
capAdjustedWords.append(word) #no capitalization
if capAdjustedWords[0].islower():
capAdjustedWords[0] = capAdjustedWords[0].capitalize() #captailize in case first word is in lowercaseWords
title = " ".join(capAdjustedWords)
#often the final char is some special character so should be removed
finalChar = title[ len(title)-1 : ]
if not finalChar.isalnum():
title = title[0 : len(title)-1] #remove the last char
return title
if __name__ == "__main__":
filepath = input("Enter the file path (using /): ")
print(getTitle(filepath))
