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Python进度条

发表于 分类于 ， Valine：
本文字数： 3k 阅读时长 ≈ 3 分钟

前言

手动实现简单进度条 or tqdm 库实现进度条。

手动实现

基本想法，利用 \r 转义符将光标退回行首然后循环打印

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import time

class ProgressBar:
    """ 进度条 """
    MAX_LENGTH = 25     # length of progress bar
    STYLE_UNDO = '*'    # show style of undo
    STYLE_DONE = '='    # show syle of finish
    def __init__(self, total=100, prefix="Loop"):
        self.cur = 0
        self.total = total
        self.prefix = prefix
    
    def restart(self, cur=None, total=None):
        if cur is not None:
            assert isinstance(cur, int), "Error type for cur: {}".format(cur)
            self.cur = cur
        if total is not None:
            assert isinstance(total, int), "Error type for total: {}".format(total)
            self.total = total

    def step(self):
        if self.cur >= self.total: return
        self.cur += 1
        undo = int(self.MAX_LENGTH * min(self.cur / self.total, 1))
        print("\r{} [{}{}{}] {:>5.2f}%".format(self.prefix, self.STYLE_DONE * (max(1, undo) - 1), '>', self.STYLE_UNDO * (self.MAX_LENGTH - undo), self.cur / self.total * 100), end='')
        if self.cur == self.total:
            print()

使用方法

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pb = ProgressBar(99)
for i in range(99):
    pb.step()
    time.sleep(0.02)

效果如下：

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> Loop [===========>*************] 50.51%
> Loop [========================>] 100.00%

升级版

  1. 添加上下文管理器
  2. 添加可迭代对象

原代码

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class ProgressBar:
    """ 进度条 """
    MAX_LENGTH = 25     # length of progress bar
    STYLE_UNDO = '*'    # show style of undo
    STYLE_DONE = '='    # show syle of finish
    def __init__(self, total=100, prefix="Loop"):
        self.cur = 0
        self.total = total
        self.prefix = prefix
    
    def restart(self, cur=None, total=None):
        if cur is not None:
            assert isinstance(cur, int), "Error type for cur: {}".format(cur)
            self.cur = cur
        if total is not None:
            assert isinstance(total, int), "Error type for total: {}".format(total)
            self.total = total

    def step(self):
        if self.cur >= self.total: return
        self.cur += 1
        undo = int(self.MAX_LENGTH * min(self.cur / self.total, 1))
        print("\r{} [{}{}{}] {:>5.2f}%".format(self.prefix, self.STYLE_DONE * (max(1, undo) - 1), '>', self.STYLE_UNDO * (self.MAX_LENGTH - undo), self.cur / self.total * 100), end='')
        if self.cur == self.total:
            print()
    
    def __enter__(self):
        return self
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        pass

    def __call__(self, obj):
        def f():
            for o in obj:
                self.step()
                yield o
        return f()

使用方法, 效果与前面相同

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with ProgressBar(1000) as pb:
    for i in pb(range(1000)):
        time.sleep(0.02)

tqdm

tqdm 是专业的实现进度条的库

基本用法

基本的使用方法是将迭代器套上一个 tqdm 类即可

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from tqdm import tqdm
for i in tqdm(range(10000)):
    time.sleep(0.001)

等价于

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from tqdm import trange
for i in trange(1000):
    time.sleep(0.001)

类似对应 enumerate, zip, map 的有 tenumerate, tzip, tmap, 即前面加上 t

可以使用类似前面手动实现的上下文管理器的方式进行更新

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with tqdm(total=87) as pbar:
    for i in range(87):
        time.sleep(0.1)
        pbar.update(1)

注意在 Python 文件和在 Jupyter 中使用不同的方法会有不同的显示风格

  • Python: from tqdm import tqdm
  • Jupyter: from tqdm.notebook import tqdm
  • (新特性)自动判断: from tqdm.autonotebook import tqdm, trange

常用参数

  • desc: 加个前缀显示
  • color: 进度条颜色，可以是 rgb 值或颜色
  • total: 手动设置循环次数
  • leave: 设置为 Fasle 则加载完就消失掉

参考资料

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