文件处理

定义

定义文件路径和文件名

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import os

dir_path = ''
file_name = ''

file_path = os.path.join(dir_path, file_name)

打开/关闭文件

读

open方式

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# 打开 open()
f = open(file_path, 'r')	# 可以是'r'可读, 'w'可写, 'a'追加, 'r+'等不停的文件默认，默认是'r'
print(f.name)	# 文件名
print(f.mode)	# 读写模式

# 是否关闭
f.closed

# 关闭 close()	避免资源泄露、锁等问题
f.close()

with方式（文件管理器处理）

with open读写文件不需要手动close。

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with open(file_path, 'r') as f:
    # content = f.read()	# 生成全文
    # content = f.readlines()	# 生成一个列表
    # content = f.readline()	# 生成一行内容
print(content)
f.closed	# => True

逐行读取

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with open(file_path, 'r') as f:
    for line in f:
        print(line, end='')

可控读取字符（每次读取100个字符）

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with open(file_path, 'r') as f:
    read_size = 100
    content = f.read(read_size)
    while len(content) > 0:
        print(content, end='*')	# 为了显示读取过程，使用'*'来断点
        content = f.read(read_size)

写

增加内容

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with open(file_path, 'a') as f:
    f.write(f'这是使用a模式所添加内容')

编写内容

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with open('./text.txt', 'w') as f:
    f.write(f'这是w模式所编写内容')
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with open('test.txt', 'w') as f:
    f.write('Test')
    f.seek(0)	# 重新定位光标
    f.wirte('R')

'''
test.txt
Rest
'''

迭代器

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class LineIterator:
    def __init__(self, file_path):
        self.file = open(file_path, 'r')

    def __iter__(self):
        return self
  
    def __next__(self):
        line = self.file.readline()
        if line:
            return line
        else:
            self.file.close()
            raise StopIteration
line_iter = LineIterator(file_path)

for line in line_iter:
    print(line)

生成器

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def line_generator(file_path):
    with open(file_path, 'r') as rf:
        for line in rf:
            yied line

line_gen = line_generator(file_path)
for line in line_gen:
    print(line)

例子

读取test.txt文档，并把它复制到新建的test2.txt文档。

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with open(file_path, 'r') as rf:
    with open('test2.txt', 'w') as wf:
        for line in rf:
            wf.write(line)

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with open(file_path, 'r') as rf:
    with open('test2.txt', 'w') as wf:
        read_siez = 10
        content = rf.read(read_size)
        while len(content) > 0:
            wf.write(content)
            content = rf.read(read_size)

复制IMG

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# xb 二进制读写
with open('dog.png', 'rb') as rf:
    with open('dog-copy.png', 'wb') as wf:
        for line in rf:
            wf.write(line)

斐波拉契数列

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def fib_generator():
    cur, nxt = 0, 1
    while True:
        yield cur
        cur, nxt = nxt, cur+nxt
fib_gen = fib_generator()

for _ in range(10):
    print(next(fib_gen))

内存使用情况

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import tracemalloc

tracemalloc.start()
'''
代码主体
'''
current, peak = tracemalloc.get_traced_memory()
print(f"Current memory usage: {cureent / 1024**2} MB")
print(f"peak memory usage: {peak / 1024**2} MB")
tracemalloc.stop()
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