Python：读取文件并排除具有某些字符的行

Question

I am trying to figure out how to write a function that opens a file and reads it, however I need it to ignore any lines that contain the character '-'

This is what I have so far:

def read_from_file(filename):
    with open('filename', 'r') as file:
        content = file.readlines()

Any help would be appreciated

Answer 1

Filter out character '-'-containing lines from your read-in lines:

filtered_lines = [x for x in content if '-' not in x]

Answer 2

I'd filter out while reading the file, not collect the unwanted lines in the first place.

def read_from_file(filename):
    with open(filename) as file:
        content = [line for line in file if '-' not in line]

Also note that the 'filename' in your open('filename', 'r') is wrong and that the 'r' is unnecessary, so I fixed/removed that.

Answer 3

Gwang-Jin Kim and Heap Overflow answers are both 100% right, but, I always feel that using the tools that Python give you to be a plus one, so here is a solution using the built-in filter() function:

list(filter(lambda line: "-" not in line, file.splitlines()))

---

def read_from_file(filename):
    with open(filename, "r") as file:
        content = filter(lambda line: "-" not in line, file.readlines())

    return list(content)

---

Here is a more verbose, yet more efficient solution:

def read_from_file(filename):

    content = []
    with open(filename, "r") as file:
        for line in file:
            if "-" not in line:
                content.append(line)

    return content