读取 csv 文件中的特定行，python

Question

在使用 python 的CSV文件中，我们可以逐行或逐行读取所有文件，我想读取特定行（行号 24 示例）而不读取所有文件和所有行。

Answer 1

You can use linecache.getline :

linecache.getline(filename, lineno[, module_globals])

Get line lineno from file named filename. This function will never raise an exception — it will return '' on errors (the terminating newline character will be included for lines that are found).

import linecache


line = linecache.getline("foo.csv",24)

Or use the consume recipe from itertools to move the pointer:

import collections
from itertools import islice

def consume(iterator, n):
    "Advance the iterator n-steps ahead. If n is none, consume entirely."
    # Use functions that consume iterators at C speed.
    if n is None:
        # feed the entire iterator into a zero-length deque
        collections.deque(iterator, maxlen=0)
    else:
        # advance to the empty slice starting at position n
        next(islice(iterator, n, n), None)

with open("foo.csv") as f:
    consume(f,23)
    line = next(f)

Answer 2

Alternatively you can leverage the nrows and skiprows argument in pandas

line_number = 30
pd.read_csv('big.csv.gz', sep = "\t", nrows = 1, skiprows = line_number - 1)

remember skiprows can be a list so if you need the header use

pd.read_csv('big.csv.gz', sep = "\t", nrows = 1, skiprows = list(range(1, line_number - 1)))