极客笔记Python tqdm模块 | 如何创建终端进度条
每当我们安装任何Python库、模块或软件时，我们都会在屏幕上看到进度条，该进度条表示估计完成或渲染该过程需要多长时间的小进度条。它给我们一种活动的印象，可以安抚神经。我们都熟悉各种进度条。其中一些有吸引力，一些则无聊。
在本文中，我们将创建进度条，而不涉及Python的核心日志记录库。
进度条根据完成任务的进度百分比而填充。可以通过将 处理的项目数 除以 总输入项目数。 计算进度。各种因素会影响进度条，例如网络速度、延迟，以及持久化数据到本地存储以得出更准确的到达预计时间（Estimated Time of Arrival，ETA）。
我们可以使用名为 Python 的外部库 tqdm 创建简单且无麻烦的进度条。我们可以将它添加到代码中，使其看起来很可爱。
tqdm在阿拉伯语中代表taqadum，意为进展。Python tqdm模块可在Linux、Windows、Mac等各种平台上工作，并且与IPython/ Jupyter笔记本 兼容。
进度条的需求
如果我们使用较小的数据集进行工作，进度不会影响我们的工作流程。然而，进度条可用于迭代数据集、训练模型或对大量信息集进行编码。
- 进度条为我们提供了已完成的过程的估计时间。
- 它向我们提供信息，即进度仍在运行，并未粗暴终止。
先决条件
系统必须安装Python 3，并且我们还可以创建虚拟环境以安装tqdm库。
安装
打开命令行终端并输入以下内容。
pip install tqdm
或者
pip3 install tqdm
上述命令将成功安装在系统中。我们可以使用以下陈述进行验证。
import tqdm
如果没有错误，则表示该库已成功安装。
为循环添加进度条
程序
import time
import sys
from tqdm import trange
def do_something():
time.sleep(1)
def do_another_something():
time.sleep(1)
for i in trange(10, file=sys.stdout, desc='outer loop'):
do_something()
for j in trange(100,file=sys.stdout, leave=False, unit_scale=True, desc='inner loop'):
do_another_something()
输出：
outer loop: 0%| | 0/10 [00:00<?, ?it/s]
inner loop: 0%| | 0.00/100 [00:00<?, ?it/s]
inner loop: 1%| | 1.00/100 [00:01<01:40, 1.02s/it]
inner loop: 2%|▏ | 2.00/100 [00:02<01:39, 1.02s/it]
inner loop: 3%|▎ | 3.00/100 [00:03<01:38, 1.01s/it]
inner loop: 4%|▍ | 4.00/100 [00:04<01:37, 1.01s/it]
inner loop: 5%|▌ | 5.00/100 [00:05<01:35, 1.01s/it]
inner loop: 6%|▌ | 6.00/100 [00:06<01:34, 1.01s/it]
inner loop: 7%|▋ | 7.00/100 [00:07<01:34, 1.01s/it]
inner loop: 8%|▊ | 8.00/100 [00:08<01:33, 1.02s/it]
inner loop: 9%|▉ | 9.00/100 [00:09<01:32, 1.02s/it]
inner loop: 10%|█ | 10.0/100 [00:10<01:31, 1.02s/it]
inner loop: 11%|█ | 11.0/100 [00:11<01:30, 1.01s/it]
inner loop: 12%|█▏ | 12.0/100 [00:12<01:29, 1.01s/it]
inner loop: 13%|█▎ | 13.0/100 [00:13<01:28, 1.01s/it]
inner loop: 14%|█▍ | 14.0/100 [00:14<01:29, 1.04s/it]
inner loop: 15%|█▌ | 15.0/100 [00:15<01:27, 1.03s/it]
inner loop: 16%|█▌ | 16.0/100 [00:16<01:26, 1.02s/it]
inner loop: 17%|█▋ | 17.0/100 [00:17<01:24, 1.02s/it]
inner loop: 18%|█▊ | 18.0/100 [00:18<01:23, 1.02s/it]
inner loop: 19%|█▉ | 19.0/100 [00:19<01:22, 1.02s/it]
…………………………………………………………………………………………….
……………………………………………………………………………………………..
It will go till it reached at 100%.
让我们来理解另一个示例。
示例 – 1
# importing modules
from tqdm import trange
from time import sleep
# creating loop
for i in trange(10, desc="loop "):
# slowing the for loop
sleep(0.1)
输出：
loop : 100%|██████████| 10/10 [00:01<00:00, 9.08it/s]
示例
# importing modules
from tqdm import tnrange
from time import sleep
# creating loop
for i in tnrange(2, dec="loop 1"):
# creating nested loop
for j in tnrange(5, dec="loop 2"):
# slowing the for loop
sleep(0.3)
输出
outer loop: 0%| | 0/10 [00:00<?, ?it/s]
inner loop: 0%| | 0.00/100 [00:00<?, ?it/s]
inner loop: 1%| | 1.00/100 [00:01<01:39, 1.00s/it]
inner loop: 2%|▏ | 2.00/100 [00:02<01:38, 1.00s/it]
inner loop: 3%|▎ | 3.00/100 [00:03<01:37, 1.00s/it]
inner loop: 4%|▍ | 4.00/100 [00:04<01:36, 1.00s/it]
inner loop: 5%|▌ | 5.00/100 [00:05<01:35, 1.00s/it]
inner loop: 6%|▌ | 6.00/100 [00:06<01:34, 1.01s/it]
inner loop: 7%|▋ | 7.00/100 [00:07<01:33, 1.01s/it]
inner loop: 8%|▊ | 8.00/100 [00:08<01:32, 1.01s/it]
inner loop: 9%|▉ | 9.00/100 [00:09<01:31, 1.00s/it]
inner loop: 10%|█ | 10.0/100 [00:10<01:30, 1.01s/it]
示例3
# importing modules
import time
import sys
from tqdm import trange
# creating random function
def random_function():
time.sleep(0.5)
# another random function
def another_random_function():
time.sleep(0.2)
# defining outer loop
for i in trange(3, file=sys.stdout, desc='Outer loop'):
random_function()
# inner loop
for j in trange(5, file=sys.stdout, desc='Inner loop'):
another_random_function()
输出:
Outer loop: 0%| | 0/3 [00:00<?, ?it/s]
Inner loop: 0%| | 0/5 [00:00<?, ?it/s]
Inner loop: 20%|██ | 1/5 [00:00<00:00, 4.62it/s]
Inner loop: 40%|████ | 2/5 [00:00<00:00, 4.64it/s]
Inner loop: 60%|██████ | 3/5 [00:00<00:00, 4.63it/s]
Inner loop: 80%|████████ | 4/5 [00:00<00:00, 4.65it/s]
Outer loop: 33%|███▎ | 1/3 [00:01<00:03, 1.58s/it]
Inner loop: 0%| | 0/5 [00:00<?, ?it/s]
Inner loop: 20%|██ | 1/5 [00:00<00:00, 4.91it/s]
Inner loop: 40%|████ | 2/5 [00:00<00:00, 4.85it/s]
Inner loop: 60%|██████ | 3/5 [00:00<00:00, 4.79it/s]
Inner loop: 80%|████████ | 4/5 [00:00<00:00, 4.77it/s]
Outer loop: 67%|██████▋ | 2/3 [00:03<00:01, 1.58s/it]
Inner loop: 0%| | 0/5 [00:00<?, ?it/s]
Inner loop: 20%|██ | 1/5 [00:00<00:00, 4.43it/s]
Inner loop: 40%|████ | 2/5 [00:00<00:00, 4.56it/s]
Inner loop: 60%|██████ | 3/5 [00:00<00:00, 4.65it/s]
Inner loop: 80%|████████ | 4/5 [00:00<00:00, 4.72it/s]
Outer loop: 100%|██████████| 3/3 [00:04<00:00, 1.57s/it]
预测性手动更新进度条
tqdm模块提供了一种手动在某些时间间隔内更新进度条的功能。当我们以块的形式下载多部分文件或以流式传输数据时，我们可以手动更新进度条函数。让我们来理解一下以下示例。
示例
# importing modules
import time
import sys
from tqdm import tqdm
def task():
time.sleep(1)
with tqdm(total=100, file=sys.stdout) as pbar:
for i in range(10):
task()
# Here we are updating progress bar manually, useful for streams such as reading files.
pbar.update(10)
# Updates in increments of 10 stops at 100
输出：
100%|██████████| 100/100 [00:10<00:00, 9.93it/s]
解释 –
在上面的代码中，我们将属性设置为100。被调用的函数在每次迭代中增加十倍，直到达到100％。我们可以将任何值传递给update()方法。
线程化进度条
我们也可以将Python tqdm包陷入Python线程中。多处理是使用总核心数的最佳方法。tqdm的位置参数允许我们指定要打印此进度条的行偏移量。在脚本未编写的情况下，默认情况下设置为自动。让我们理解以下示例。必须提供该值以同时管理多个进度条。如果忽略此参数，我们的进度条将被不同的线程覆盖。
示例
import time
from random import randrange
from multiprocessing.pool import ThreadPool
from tqdm import tqdm
def func_call(position, total):
text = 'progressbar #{position}'.format(position=position)
with tqdm(total=total, position=position, desc=text) as progress:
for _ in range(0, total, 5):
progress.update(5)
time.sleep(randrange(3))
pool = ThreadPool(10)
tasks = range(5)
for i, url in enumerate(tasks, 1):
pool.apply_async(func_call, args=(i, 100))
pool.close()
pool.join()
输出：
progressbar #5: 0%| | 0/100 [00:00<?, ?it/s]
progressbar #2: 0%| | 0/100 [00:00<?, ?it/s]
progressbar #1: 0%| | 0/100 [00:00<?, ?it/s]
progressbar #4: 0%| | 0/100 [00:00<?, ?it/s]
progressbar #3: 0%| | 0/100 [00:00<?, ?it/s]
progressbar #3: 10%|█ | 10/100 [00:01<00:09, 9.91it/s]
progressbar #5: 10%|█ | 10/100 [00:01<00:09, 9.91it/s]
progressbar #1: 10%|█ | 10/100 [00:02<00:18, 4.97it/s]
progressbar #2: 10%|█ | 10/100 [00:02<00:18, 4.96it/s]
progressbar #4: 10%|█ | 10/100 [00:02<00:18, 4.96it/s]
progressbar #5: 15%|█▌ | 15/100 [00:02<00:11, 7.64it/s]
progressbar #3: 15%|█▌ | 15/100 [00:02<00:11, 7.64it/s]
progressbar #4: 15%|█▌ | 15/100 [00:03<00:17, 4.96it/s]
progressbar #2: 15%|█▌ | 15/100 [00:03<00:17, 4.95it/s]
progressbar #3: 20%|██ | 20/100 [00:04<00:16, 4.71it/s]
progressbar #5: 25%|██▌ | 25/100 [00:04<00:11, 6.58it/s]
progressbar #1: 20%|██ | 20/100 [00:04<00:16, 4.97it/s]
progressbar #2: 20%|██ | 20/100 [00:04<00:16, 4.96it/s]
在Tqdm进度条中添加颜色
颜色可以使进度条非常吸引人。然而，它并不会为进度条的工作方式添加任何新功能。tqdm可以与Colorama一起工作，Colorama是一个简单的跨平台颜色终端文本库。让我们来看下面的示例。
示例
from tqdm import trange
from colorama import Fore
# Cross-platform colored terminal text.
color_bars = [Fore.BLACK,
Fore.RED,
Fore.GREEN,
Fore.YELLOW,
Fore.BLUE,
Fore.MAGENTA,
Fore.CYAN,
Fore.WHITE]
for color in color_bars:
for i in trange(int(7e7),
bar_format="{l_bar}%s{bar}%s{r_bar}" % (color, Fore.RESET)):
pass
输出：
结论
我们讨论了与进度条相关的所有基本概念。Python提供了tqdm模块，可以帮助我们进行手动设计。我们为tqdm模块中可以执行的重要操作定义了适用的示例。tqdm模块可以与子进程和线程协作，可以同时运行多个进度条。