在包含字符串的文本文件中打印行

Question

我試圖獲取包含特定字符串的文本文件的行，並在行中打印第三個數字或字符串。該文本文件看起來像：

1997 180 60 bob 

1997 145 59 dan 

如果輸入的文本包含bob，我的代碼應打印60。

這是我到目前爲止有：

calWeight = [line for line in open('user_details.txt') if name in line] 
stringCalWeight = str(calWeight) 
print (stringCalWeight) 

我怎樣才能解決呢？

Answer 1

with open('user_details.txt') as f: 
    for line in f: 
     if "bob" in line: 
      print(line.split()[2]) 

如果希望所有NUMS其中鮑勃是在該行的列表中使用列表理解：

with open('user_details.txt') as f: 
    nums = [line.split()[2] for line in f if "bob" in line] 

你也可能需要分割你檢查之前，如果你想避免的情況下名稱是行的串子串，例如bob in bobbing - >真：

nums = [line.split()[2] for line in f if "bob" in line.split()] 

我認爲更有用的結構將是一個字典，其中值都在一條線上阿索第三號與每個名稱相關：

from collections import defaultdict 
d = defaultdict(list) 
with open("in.txt") as f: 
    for line in f: 
     if line.strip(): 
      spl = line.rstrip().split() 
      d[spl[-1]].append(spl[2]) 
print(d) 
defaultdict(<type 'list'>, {'bob': ['60'], 'dan': ['59']}) 

Answer 2

通過re模塊。

>>> L = [] 
>>> for line in open('/home/avinash/Desktop/f'): 
     if 'bob' in line: 
      L.append(re.search(r'^(?:\D*\d+\b){2}\D*(\d+)', line).group(1)) 


>>> print(L) 
['60'] 

Answer 3

#need to open the file properly 
with open('info.txt', 'r') as fp: 
    #as suggested by @Padraic Cunningham it is better to iterate over the file object 
    for line in fp: 
     #each piece of information goes in a list 
     infos = line.split() 
     #this makes sure that there are no problems if your file has a empty line 
     #and finds bob in the information 
     if infos and infos[-1] == 'bob': 
      print (infos[2])