我们有一个很大的原始数据文件,我们想把它修剪成指定的大小。

如何在python中获取文本文件的前N行?所使用的操作系统对实现有任何影响吗?


当前回答

有一个简单的方法来获取前10行:

with open('fileName.txt', mode = 'r') as file:
    list = [line.rstrip('\n') for line in file][:10]
    print(list)

其他回答

这对我很有效

f = open("history_export.csv", "r")
line= 5
for x in range(line):
    a = f.readline()
    print(a)

没有特定的方法来读取文件对象暴露的行数。

我想最简单的方法是:

lines =[]
with open(file_name) as f:
    lines.extend(f.readline() for i in xrange(N))

有一个简单的方法来获取前10行:

with open('fileName.txt', mode = 'r') as file:
    list = [line.rstrip('\n') for line in file][:10]
    print(list)

fname = input("Enter file name: ")
num_lines = 0

with open(fname, 'r') as f: #lines count
    for line in f:
        num_lines += 1

num_lines_input = int (input("Enter line numbers: "))

if num_lines_input <= num_lines:
    f = open(fname, "r")
    for x in range(num_lines_input):
        a = f.readline()
        print(a)

else:
    f = open(fname, "r")
    for x in range(num_lines_input):
        a = f.readline()
        print(a)
        print("Don't have", num_lines_input, " lines print as much as you can")


print("Total lines in the text",num_lines)

Python 3:

with open("datafile") as myfile:
    head = [next(myfile) for x in range(N)]
print(head)

Python 2:

with open("datafile") as myfile:
    head = [next(myfile) for x in xrange(N)]
print head

下面是另一种方法(Python 2和3都是):

from itertools import islice

with open("datafile") as myfile:
    head = list(islice(myfile, N))
print(head)