Python - 从文本文件中查找行号
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Python - Find line number from text file
提问by googlecoolcat
I'm writing code that looks in a text file, and sees if the input is in there.
我正在编写在文本文件中查找的代码，并查看输入是否在其中。
E.g.,
例如，
I input "pizza"
我输入"比萨"
My textfile contains:
我的文本文件包含：
bread
pizza
pasta
tomato
Is there a way to print the line number the word pizza is on?
有没有办法打印披萨这个词所在的行号？
采纳答案by Oxymoron88
with open('test.txt') as f:
content = f.readlines()
index = [x for x in range(len(content)) if 'pizza' in content[x].lower()]
Part (1) of the code reads each line as a separate list in variable "content".
代码的第 (1) 部分将每一行读取为变量“内容”中的单独列表。
Part (2) populates out the line # of content only if 'pizza' exists in that line. [x for x in range(len(content))] simply populates all index values, while 'if 'pizza' in content[x].lower()' keeps the line # that matches the string.
仅当“pizza”存在于该行中时，第 (2) 部分才会填充该行 # 的内容。[x for x in range(len(content))] 只是填充所有索引值，而 'if 'pizza' in content[x].lower()' 保留与字符串匹配的行 #。
回答by Rushy Panchal
There are two ways of accomplishing this:
有两种方法可以实现这一点：
- Storing the entire file in memory so you only read it once
- Reading through the file on every search, but not having to store it
- 将整个文件存储在内存中，以便您只能读取一次
- 在每次搜索时通读文件，但不必存储它
For method 1, first read in every line and then get the index that the word is on:
对于方法1，首先读取每一行，然后获取单词所在的索引：
with open('path.txt') as f: data = f.readlines()
line_no = data.index("pizza")
Alternatively, go through the file to find the index:
或者，通过文件查找索引：
with open('path.txt') as f:
for line_no, line in enumerate(f):
if line == "pizza":
break
else: # for loop ended => line not found
line_no = -1
回答by Valentin B.
Something like this:
像这样的东西：
import re
import os # You can go without is if you have other means to get your filepath
i = 1
matches = []
target = raw_input("Please type string to match\n")
with open(os.getenv("SOME_PATH") + "/myfile.txt") as fic: # open("myfile.txt") if in your current directory
for line in fic:
if re.search(target, line):
print "Found at line {}".format(i)
matches.append(i)
i = i +1
if not len(matches):
raise Exception, "target not found"
By doing this, you can input a regular expression and it should work (i.e. if you input "p.zza" or "^p.*", it will work.). The list matcheswill contain all indices of lines that match the input pattern.
通过这样做，您可以输入一个正则表达式，它应该可以工作（即，如果您输入“p.zza”或“^p.*”，它就会工作。）。该列表matches将包含与输入模式匹配的所有行索引。
回答by Joran Beasley
print next (i for i,v in enumerate (open (fname),1) if v == needle)
