Python 常用库：tqdm

tqdm

tqdm 是一个快速，可扩展的 Python 进度条，可以在 Python 长循环中添加一个进度提示信息，用户只需要封装任意的迭代器 tqdm (iterator)。

使用 pip 就可以安装。

pip install tqdm

用例一：tqdm

tqdm (list) 方法可以传入任意一种 list, 比如数组

import time
from tqdm import tqdm

for i in tqdm(range(1000)):  
     #do something
     time.sleep(0.5)  

用例二：trange

trange (i) 是 tqdm (range (i)) 的简单写法

from tqdm import trange
for i in trange(100):
    #do something
    pass

用例三：带参数

from tqdm import tqdm
import time
d = {
     'loss':0.2,'learn':0.8}
#desc设置名称, ncols设置进度条长度, postfix以字典形式传入详细信息
for i in tqdm(range(50), desc='进行中', postfix=d): 
    time.sleep(0.1)

效果

用例四：用 tqdm 处理列表中的对象，显示处理进度

import time
from tqdm import tqdm

bar = tqdm(['p1','p2','p3','p4','p5'])
for b in bar:
    bar.set_description("处理 {0} 中".format(b))
    time.sleep(0.5)

效果

更多用例：

class tqdm(Comparable):
	def __init__(self, iterable=None, desc=None, total=None, leave=True,
                 file=None, ncols=None, mininterval=0.1, maxinterval=10.0,
                 miniters=None, ascii=None, disable=False, unit='it',
                 unit_scale=False, dynamic_ncols=False, smoothing=0.3,
                 bar_format=None, initial=0, position=None, postfix=None,
                 unit_divisor=1000, write_bytes=None, lock_args=None,
                 nrows=None,
                 gui=False, **kwargs):

参数：

• desc：进度条的前缀
• ncols：输出信息的宽度。注意：如果设置的宽度过窄，将导致输出的信息显示不全！

完整说明如下：

        Parameters
        ----------
        iterable  : iterable, optional
            Iterable to decorate with a progressbar.
            Leave blank to manually manage the updates.
        desc  : str, optional
            Prefix for the progressbar.
        total  : int or float, optional
            The number of expected iterations. If unspecified,
            len(iterable) is used if possible. If float("inf") or as a last
            resort, only basic progress statistics are displayed
            (no ETA, no progressbar).
            If `gui` is True and this parameter needs subsequent updating,
            specify an initial arbitrary large positive number,
            e.g. 9e9.
        leave  : bool, optional
            If [default: True], keeps all traces of the progressbar
            upon termination of iteration.
            If `None`, will leave only if `position` is `0`.
        file  : `io.TextIOWrapper` or `io.StringIO`, optional
            Specifies where to output the progress messages
            (default: sys.stderr). Uses `file.write(str)` and `file.flush()`
            methods.  For encoding, see `write_bytes`.
        ncols  : int, optional
            The width of the entire output message. If specified,
            dynamically resizes the progressbar to stay within this bound.
            If unspecified, attempts to use environment width. The
            fallback is a meter width of 10 and no limit for the counter and
            statistics. If 0, will not print any meter (only stats).
        mininterval  : float, optional
            Minimum progress display update interval [default: 0.1] seconds.
        maxinterval  : float, optional
            Maximum progress display update interval [default: 10] seconds.
            Automatically adjusts `miniters` to correspond to `mininterval`
            after long display update lag. Only works if `dynamic_miniters`
            or monitor thread is enabled.
        miniters  : int or float, optional
            Minimum progress display update interval, in iterations.
            If 0 and `dynamic_miniters`, will automatically adjust to equal
            `mininterval` (more CPU efficient, good for tight loops).
            If > 0, will skip display of specified number of iterations.
            Tweak this and `mininterval` to get very efficient loops.
            If your progress is erratic with both fast and slow iterations
            (network, skipping items, etc) you should set miniters=1.
        ascii  : bool or str, optional
            If unspecified or False, use unicode (smooth blocks) to fill
            the meter. The fallback is to use ASCII characters " 123456789#".
        disable  : bool, optional
            Whether to disable the entire progressbar wrapper
            [default: False]. If set to None, disable on non-TTY.
        unit  : str, optional
            String that will be used to define the unit of each iteration
            [default: it].
        unit_scale  : bool or int or float, optional
            If 1 or True, the number of iterations will be reduced/scaled
            automatically and a metric prefix following the
            International System of Units standard will be added
            (kilo, mega, etc.) [default: False]. If any other non-zero
            number, will scale `total` and `n`.
        dynamic_ncols  : bool, optional
            If set, constantly alters `ncols` and `nrows` to the
            environment (allowing for window resizes) [default: False].
        smoothing  : float, optional
            Exponential moving average smoothing factor for speed estimates
            (ignored in GUI mode). Ranges from 0 (average speed) to 1
            (current/instantaneous speed) [default: 0.3].
        bar_format  : str, optional
            Specify a custom bar string formatting. May impact performance.
            [default: '{l_bar}{bar}{r_bar}'], where
            l_bar='{desc}: {percentage:3.0f}%|' and
            r_bar='| {n_fmt}/{total_fmt} [{elapsed}<{remaining}, '
              '{rate_fmt}{postfix}]'
            Possible vars: l_bar, bar, r_bar, n, n_fmt, total, total_fmt,
              percentage, elapsed, elapsed_s, ncols, nrows, desc, unit,
              rate, rate_fmt, rate_noinv, rate_noinv_fmt,
              rate_inv, rate_inv_fmt, postfix, unit_divisor,
              remaining, remaining_s.
            Note that a trailing ": " is automatically removed after {
     desc}
            if the latter is empty.
        initial  : int or float, optional
            The initial counter value. Useful when restarting a progress
            bar [default: 0]. If using float, consider specifying `{
     n:.3f}`
            or similar in `bar_format`, or specifying `unit_scale`.
        position  : int, optional
            Specify the line offset to print this bar (starting from 0)
            Automatic if unspecified.
            Useful to manage multiple bars at once (eg, from threads).
        postfix  : dict or *, optional
            Specify additional stats to display at the end of the bar.
            Calls `set_postfix(**postfix)` if possible (dict).
        unit_divisor  : float, optional
            [default: 1000], ignored unless `unit_scale` is True.
        write_bytes  : bool, optional
            If (default: None) and `file` is unspecified,
            bytes will be written in Python 2. If `True` will also write
            bytes. In all other cases will default to unicode.
        lock_args  : tuple, optional
            Passed to `refresh` for intermediate output
            (initialisation, iterating, and updating).
        nrows  : int, optional
            The screen height. If specified, hides nested bars outside this
            bound. If unspecified, attempts to use environment height.
            The fallback is 20.
        gui  : bool, optional
            WARNING: internal parameter - do not use.
            Use tqdm.gui.tqdm(...) instead. If set, will attempt to use
            matplotlib animations for a graphical output [default: False].

        Returns
        -------
        out  : decorated iterator.

参考：

https://blog.csdn.net/zkp_987/article/details/81748098

https://blog.csdn.net/feiyang5260/article/details/100050539