Python从文本中解析特定单词

Question

我希望在一篇文章中统计一下“血”这个词的具体提及次数，但我还没有走得太远。我已经尝试了几种方法，最大的收获是能够解析出包含该单词的所有句子。这就是我到目前为止得到的结果，它以退出代码0结束

 infile = open('C:\IS452\week7\dracula.txt', 'rt', encoding = 'utf=8')
    dracula_lines = infile.readlines()
    infile.close()

    for blood_lines in dracula_lines:

    accumulator = blood_lines.strip()


    dracula_lines.count("blood")
    if "blood" in dracula_lines:
        print("blood") in str(newText[blood_lines + 1])
    #print(blood_lines)

    blood_lines = accumulator.split("blood")
    newText = ("There are this many mentions of blood in Dracula", blood_lines)
      print(newText)

Answer 1

你可以直接在字符串上使用.count()：

with open('C:\IS452\week7\dracula.txt', 'r', encoding = 'utf=8') as f:
  dracula_txt = f.read().lower()

blood_count = dracula_txt.count("blood")
print(blood_count, "mentions of blood in Dracula")

如果您这样做是为了一些编码挑战，而不允许只使用.count()，那么您可以这样做：

dracula_list = dracula_txt.split("blood") # split text into list separated by occurrences of "blood"
blood_count = len(dracula_list) - 1 # count of occurrences is the length of the list minus one

如果你认为这也是作弊，那么你可以试着这样做：

index = blood_count = 0
while(index != -1):
  try:
    # we get the position of the next occurrence of "blood" in the string, starting from the position of the last occurrence plus one
    index = dracula_txt.index("blood", index) + 1
    blood_count += 1
  except ValueError: # when there aren't any more occurrences of "blood" in the string, we get a ValueError and exit the loop 
    index = -1
print(blood_count, "mentions of blood in Dracula")

或者您可以遍历字符串中的每个字符，检查字符索引后面的子字符串是否与“and”匹配，并相应地递增计数：

blood_count = 0
for i in range(0, len(dracula_txt)):
    if dracula_txt[i:i+5] == "blood":
        blood_count += 1
print(blood_count)