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))

这里有另一个不错的解决方案与列表理解:

file = open('file.txt', 'r')

lines = [next(file) for x in range(3)]  # first 3 lines will be in this list

file.close()

这对我很有效

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

最直观的两种方法是:

逐行迭代文件，并在N行之后进行换行。 使用next()方法逐行迭代文件N次。(这本质上只是顶部答案的不同语法。)

代码如下:

# Method 1:
with open("fileName", "r") as f:
    counter = 0
    for line in f:
        print line
        counter += 1
        if counter == N: break

# Method 2:
with open("fileName", "r") as f:
    for i in xrange(N):
        line = f.next()
        print line

底线是，只要不使用readlines()或将整个文件枚举到内存中，您就有很多选择。

N = 10
with open("file.txt", "a") as file:  # the a opens it in append mode
    for i in range(N):
        line = next(file).strip()
        print(line)