Pythonでprintの上書きをする方法

print("\r"+"一行を上書きします！",end="")

import time
import sys

def countdown(seconds):
    for i in range(seconds, 0, -1):
        # \rで行頭に戻り、上書き表示
        sys.stdout.write(f"\r残り {i:3d} 秒")
        sys.stdout.flush()
        time.sleep(1)
    sys.stdout.write("\r完了！          \n")

countdown(10)

import sys
import time
import itertools

def spinning_cursor(duration=5):
    spinner = itertools.cycle(['|', '/', '-', '\\'])
    end_time = time.time() + duration
    while time.time() < end_time:
        sys.stdout.write(f"\r処理中... {next(spinner)}")
        sys.stdout.flush()
        time.sleep(0.1)
    sys.stdout.write("\r処理完了！     \n")

spinning_cursor(3)

import sys

def my_print(*objects, sep=" ", end="\n", file=None, flush=False):
    if file is None:
        file = sys.stdout
    file.write(sep.join(str(obj) for obj in objects) + end)
    if flush:
        file.flush()

>>> import io
>>> io.DEFAULT_BUFFER_SIZE
131072

import sys
import time

for i in range(5):
    print(f"stdout {i}")               # sys.stdout 経由（バッファリングモードは接続先次第）
    sys.stderr.write(f"stderr {i}\n")  # sys.stderr は常にバッファリングされない
    time.sleep(0.15)

t=0.018s [STDOUT] stdout 0
t=0.018s [STDERR] stderr 0
t=0.169s [STDOUT] stdout 1
t=0.169s [STDERR] stderr 1
t=0.321s [STDOUT] stdout 2
t=0.321s [STDERR] stderr 2
t=0.476s [STDOUT] stdout 3
t=0.476s [STDERR] stderr 3
t=0.631s [STDOUT] stdout 4
t=0.631s [STDERR] stderr 4

t=0.020s [STDERR] stderr 0
t=0.172s [STDERR] stderr 1
t=0.327s [STDERR] stderr 2
t=0.481s [STDERR] stderr 3
t=0.632s [STDERR] stderr 4
t=0.787s [STDOUT] stdout 0
t=0.787s [STDOUT] stdout 1
t=0.787s [STDOUT] stdout 2
t=0.787s [STDOUT] stdout 3
t=0.787s [STDOUT] stdout 4

# 方法1: print() ごとに flush=True を指定
print(f"stdout {i}", flush=True)

# 方法2: インタプリタ起動時に -u（unbuffered）オプションを付ける
# $ python3 -u script.py > out.txt

print("最初の行")
print("二番目の行")
# カーソルを1行上に移動し、上書き
print("\033[1A新しい二番目の行")

# 成功時は緑、失敗時は赤で表示
def print_status(message, success=True):
    color = "\033[32m" if success else "\033[31m"
    reset = "\033[0m"
    print(f"{color}{message}{reset}")

print_status("テスト通過", success=True)
print_status("テスト失敗", success=False)

import sys
import time

def download_progress(total_size, chunk_size=1024):
    """ダウンロード進捗をプログレスバーで表示する"""
    downloaded = 0
    bar_length = 40

    while downloaded < total_size:
        downloaded += chunk_size
        if downloaded > total_size:
            downloaded = total_size

        # 進捗率の計算
        progress = downloaded / total_size
        filled = int(bar_length * progress)
        bar = "█" * filled + "░" * (bar_length - filled)

        # MB単位で表示
        dl_mb = downloaded / (1024 * 1024)
        total_mb = total_size / (1024 * 1024)

        # 色付きで進捗表示
        if progress < 0.5:
            color = "\033[33m"  # 黄色
        else:
            color = "\033[32m"  # 緑色
        reset = "\033[0m"

        sys.stdout.write(
            f"\r{color}[{bar}]{reset} "
            f"{progress:6.1%} "
            f"({dl_mb:.1f}/{total_mb:.1f} MB)"
        )
        sys.stdout.flush()
        time.sleep(0.01)  # ダウンロードのシミュレーション

    sys.stdout.write("\n")
    print("ダウンロード完了！")

# 10MBのファイルをシミュレーション
download_progress(10 * 1024 * 1024, chunk_size=100 * 1024)

import sys
import time
import random

def multi_task_progress():
    """複数タスクの進捗を同時更新する"""
    tasks = ["データ取得", "前処理  ", "学習    ", "評価    "]
    progress = [0] * len(tasks)

    # 初期表示
    for task in tasks:
        print(f"  {task}: [{'░' * 30}]   0%")

    while not all(p >= 100 for p in progress):
        # ランダムに進捗を更新
        for i in range(len(tasks)):
            if progress[i] < 100:
                progress[i] = min(100, progress[i] + random.randint(0, 5))

        # カーソルをタスク数分上に移動
        sys.stdout.write(f"\033[{len(tasks)}A")

        for i, task in enumerate(tasks):
            filled = int(30 * progress[i] / 100)
            bar = "█" * filled + "░" * (30 - filled)
            if progress[i] >= 100:
                color = "\033[32m"  # 完了: 緑
            else:
                color = "\033[33m"  # 進行中: 黄
            reset = "\033[0m"
            print(f"  {task}: {color}[{bar}]{reset} {progress[i]:3d}%")

        time.sleep(0.1)

multi_task_progress()

import timeit

progress = 0.6428
dl_mb = 6.428
total_mb = 10.0
bar = "#" * 25 + "-" * 15

def with_fstring():
    return f"\r[{bar}] {progress:6.1%} ({dl_mb:.1f}/{total_mb:.1f} MB)"

def with_format():
    return "\r[{}] {:6.1%} ({:.1f}/{:.1f} MB)".format(bar, progress, dl_mb, total_mb)

def with_percent():
    return "\r[%s] %5.1f%% (%.1f/%.1f MB)" % (bar, progress * 100, dl_mb, total_mb)

N = 2_000_000
for name, fn in [("f-string", with_fstring), (".format()", with_format), ("%-formatting", with_percent)]:
    best = min(timeit.repeat(fn, number=N, repeat=5))
    print(f"{name:14s}: {best / N * 1e9:.1f} ns/call")

# pip install colorama
from colorama import init, Fore, Style

# WindowsでANSIエスケープを有効化
init()

# coloramaを使った色付き出力
print(Fore.GREEN + "成功" + Style.RESET_ALL)
print(Fore.RED + "エラー" + Style.RESET_ALL)

import os
import sys

def supports_ansi():
    """ANSIエスケープシーケンスが使えるか判定"""
    if os.name == "nt":
        # Windows 10 build 10586以降はサポート
        return os.environ.get("WT_SESSION") is not None  # Windows Terminal
    return hasattr(sys.stdout, "isatty") and sys.stdout.isatty()

if supports_ansi():
    GREEN = "\033[32m"
    RESET = "\033[0m"
else:
    GREEN = ""
    RESET = ""

print(f"{GREEN}ステータス: OK{RESET}")

import sys

print("stdout encoding:", sys.stdout.encoding)
print(f"進捗 100% 完了 ✅")

$ PYTHONIOENCODING=cp1252 python3 encoding_bug.py
stdout encoding: cp1252
Traceback (most recent call last):
  File "encoding_bug.py", line 4, in <module>
    print(f"進捗 100% 完了 ✅")
UnicodeEncodeError: 'charmap' codec can't encode characters in position 0-1: character maps to <undefined>

$ PYTHONIOENCODING=utf-8 python3 encoding_bug.py
stdout encoding: utf-8
進捗 100% 完了 ✅

import sys

sys.stdout.reconfigure(encoding="utf-8")
print("stdout encoding after reconfigure:", sys.stdout.encoding)
print(f"進捗 100% 完了 ✅")

stdout encoding after reconfigure: utf-8
進捗 100% 完了 ✅

from rich.console import Console
from rich.table import Table

console = Console()

# プログレス表示
from rich.progress import track
import time

for i in track(range(100), description="Processing..."):
    time.sleep(0.01)

# ステータス表示（スピナー付き）
with console.status("Computing..."):
    time.sleep(2)
    console.print("[bold green]Done![/bold green]")

from tqdm import tqdm
import time

for i in tqdm(range(100)):
    time.sleep(0.01)