从基础到高级详解Python文本对齐完全指南

text = "python"

# 左对齐（默认）
left = text.ljust(10)       # 'python    '
center = text.center(10)   # '  python  '
right = text.rjust(10)     # '    python'

# 自定义填充字符
filled = text.center(15, '*')  # '****python****'

# 旧式格式化
print("|%10s|" % text)     # '|    python|'
print("|%-10s|" % text)    # '|python    |'

# format方法
print("|{:>10}|".format(text))   # 右对齐
print("|{:<10}|".format(text))   # 左对齐
print("|{:^10}|".format(text))   # 居中对齐
print("|{:*^10}|".format(text))  # 填充对齐

# f-string (python 3.6+)
width = 10
print(f"|{text:>{width}}|")      # 右对齐
print(f"|{text:<{width}}|")      # 左对齐
print(f"|{text:^{width}}|")      # 居中对齐
print(f"|{text:*^{width}}|")     # 填充对齐

import textwrap

long_text = "python is an interpreted, high-level and general-purpose programming language."

# 基础换行
wrapped = textwrap.fill(long_text, width=30)
print(wrapped)
"""
python is an interpreted,
high-level and general-purpose
programming language.
"""

# 高级排版
formatted = textwrap.fill(
    long_text,
    width=30,
    initial_indent='> ',    # 首行缩进
    subsequent_indent='| '   # 后续行缩进
)
print(formatted)
"""
> python is an interpreted,
| high-level and general-
| purpose programming
| language.
"""

def format_code_block(code, width=80):
    """格式化代码块"""
    # 移除多余空白
    code = '\n'.join(line.rstrip() for line in code.split('\n'))
    
    # 智能缩进处理
    dedented = textwrap.dedent(code)
    
    # 保持注释对齐
    wrapped = []
    for line in dedented.split('\n'):
        if line.strip().startswith('#'):
            # 注释行保持原样
            wrapped.append(line)
        else:
            # 代码行换行处理
            wrapped.extend(textwrap.wrap(line, width=width))
    
    return '\n'.join(wrapped)

# 测试
code = """
    def calculate(a, b):
        # 这是一个加法函数
        result = a + b  # 计算结果
        return result
"""
print(format_code_block(code, 40))
"""
def calculate(a, b):
    # 这是一个加法函数
    result = a + b  # 计算结果
    return result
"""

def generate_table(data, headers, col_width=15):
    """生成对齐的文本表格"""
    # 表头分隔线
    separator = '+' + '+'.join(['-' * col_width] * len(headers)) + '+'
    
    # 构建表头
    header_line = '|' + '|'.join(
        f"{h:^{col_width}}" for h in headers
    ) + '|'
    
    # 构建数据行
    rows = []
    for row in data:
        row_line = '|' + '|'.join(
            f"{str(cell):^{col_width}}" for cell in row
        ) + '|'
        rows.append(row_line)
    
    # 组合表格
    return '\n'.join([separator, header_line, separator] + rows + [separator])

# 使用示例
headers = ["product", "price", "stock"]
data = [
    ["laptop", 999.99, 15],
    ["phone", 699.99, 30],
    ["tablet", 399.99, 25]
]

print(generate_table(data, headers))
"""
+---------------+---------------+---------------+
|    product    |     price     |     stock     |
+---------------+---------------+---------------+
|    laptop     |    999.99     |      15       |
|    phone      |    699.99     |      30       |
|    tablet     |    399.99     |      25       |
+---------------+---------------+---------------+
"""

class tableformatter:
    """高级表格格式化器"""
    def __init__(self, headers, alignments=none, float_precision=2):
        self.headers = headers
        self.alignments = alignments or ['^'] * len(headers)
        self.float_precision = float_precision
        self.col_widths = [len(h) for h in headers]
    
    def update_widths(self, row):
        for i, cell in enumerate(row):
            if isinstance(cell, float):
                cell_str = f"{cell:.{self.float_precision}f}"
            else:
                cell_str = str(cell)
            self.col_widths[i] = max(self.col_widths[i], len(cell_str))
    
    def format_row(self, row):
        formatted = []
        for i, cell in enumerate(row):
            width = self.col_widths[i]
            align = self.alignments[i]
            
            if isinstance(cell, float):
                cell_str = f"{cell:.{self.float_precision}f}"
            else:
                cell_str = str(cell)
            
            formatted.append(f"{cell_str:{align}{width}}")
        return '| ' + ' | '.join(formatted) + ' |'
    
    def format_table(self, data):
        # 计算列宽
        for row in data:
            self.update_widths(row)
        
        # 生成分隔线
        separator = '+-' + '-+-'.join(
            '-' * w for w in self.col_widths
        ) + '-+'
        
        # 生成表头
        header_row = self.format_row(self.headers)
        
        # 生成数据行
        data_rows = [self.format_row(row) for row in data]
        
        return '\n'.join([separator, header_row, separator] + data_rows + [separator])

# 使用示例
headers = ["product", "price", "stock", "rating"]
data = [
    ["laptop", 999.99, 15, 4.5],
    ["phone", 699.99, 30, 4.7],
    ["tablet", 399.99, 25, 4.3]
]

formatter = tableformatter(
    headers,
    alignments=['<', '>', '>', '^'],  # 左对齐，右对齐，右对齐，居中
    float_precision=2
)

print(formatter.format_table(data))
"""
+----------+--------+-------+--------+
| product  |  price | stock | rating |
+----------+--------+-------+--------+
| laptop   | 999.99 |    15 |  4.5   |
| phone    | 699.99 |    30 |  4.7   |
| tablet   | 399.99 |    25 |  4.3   |
+----------+--------+-------+--------+
"""

def color_text(text, color_code):
    """添加ansi颜色"""
    return f"\033[{color_code}m{text}\033[0m"

def format_colored_table(data, headers, colors):
    """带颜色的表格"""
    formatter = tableformatter(headers)
    for row in data:
        formatter.update_widths(row)
    
    # 生成表头
    header_line = formatter.format_row([
        color_text(h, colors.get(h, '0')) for h in headers
    ])
    
    # 生成数据行
    data_lines = []
    for row in data:
        colored_row = []
        for i, cell in enumerate(row):
            header = headers[i]
            color = colors.get(header, '0')
            cell_str = str(cell)
            if isinstance(cell, float):
                cell_str = f"{cell:.2f}"
            colored_row.append(color_text(cell_str, color))
        data_lines.append(formatter.format_row(colored_row))
    
    # 生成分隔线
    separator = '+-' + '-+-'.join(
        '-' * w for w in formatter.col_widths
    ) + '-+'
    
    return '\n'.join([separator, header_line, separator] + data_lines + [separator])

# 使用示例
headers = ["name", "age", "score"]
data = [
    ["alice", 28, 95.5],
    ["bob", 32, 88.2],
    ["charlie", 25, 91.8]
]

colors = {
    "name": "34",   # 蓝色
    "age": "33",     # 黄色
    "score": "32"    # 绿色
}

print(format_colored_table(data, headers, colors))

def format_progress_bar(progress, width=50, label=""):
    """对齐的进度条"""
    # 计算进度块
    filled = int(progress * width)
    bar = '[' + '#' * filled + ' ' * (width - filled) + ']'
    
    # 添加百分比
    percent = f"{progress * 100:.1f}%"
    
    # 对齐标签
    label_width = 15
    aligned_label = f"{label:<{label_width}}"
    
    # 组合所有元素
    return f"{aligned_label} {bar} {percent}"

# 测试
print(format_progress_bar(0.25, label="processing"))
print(format_progress_bar(0.75, label="analyzing"))
print(format_progress_bar(1.0, label="completed"))

"""
processing     [####################                          ] 25.0%
analyzing      [######################################        ] 75.0%
completed      [##################################################] 100.0%
"""

import logging
from logging import formatter

class alignedformatter(formatter):
    """对齐的日志格式化器"""
    def __init__(self, fmt=none, datefmt=none, style='%', align_width=10):
        super().__init__(fmt, datefmt, style)
        self.align_width = align_width
    
    def format(self, record):
        # 对齐日志级别
        record.levelname = record.levelname.ljust(self.align_width)
        
        # 对齐模块名
        if hasattr(record, 'module'):
            record.module = record.module.ljust(self.align_width)
        
        return super().format(record)

# 配置日志
logger = logging.getlogger("app")
handler = logging.streamhandler()

formatter = alignedformatter(
    fmt='%(asctime)s | %(levelname)s | %(module)s | %(message)s',
    datefmt='%y-%m-%d %h:%m:%s',
    align_width=10
)

handler.setformatter(formatter)
logger.addhandler(handler)
logger.setlevel(logging.debug)

# 测试日志
logger.debug("starting application")
logger.info("configuration loaded")
logger.warning("resource usage high")
logger.error("failed to connect to database")

"""
2023-08-15 14:30:22 | debug      | __main__    | starting application
2023-08-15 14:30:23 | info       | config      | configuration loaded
2023-08-15 14:30:25 | warning    | monitor     | resource usage high
2023-08-15 14:30:30 | error      | database    | failed to connect to database
"""

def format_exception(exc):
    """美化异常堆栈输出"""
    import traceback
    
    # 获取堆栈信息
    tb_lines = traceback.format_exception(type(exc), exc, exc.__traceback__)
    
    # 对齐处理
    formatted = []
    for line in tb_lines:
        # 对齐文件路径
        if "file" in line:
            parts = line.split(',')
            if len(parts) >= 2:
                file_info = parts[0].strip()
                code_info = ','.join(parts[1:]).strip()
                aligned = f"  {file_info:<50} {code_info}"
                formatted.append(aligned)
            else:
                formatted.append(line)
        else:
            formatted.append(line)
    
    return ''.join(formatted)

# 测试
try:
    1 / 0
except exception as e:
    print(format_exception(e))

"""
  file "<stdin>", line 2                     in <module>
zerodivisionerror: division by zero
"""

def justify_text(text, width):
    """两端对齐文本"""
    words = text.split()
    lines = []
    current_line = []
    current_length = 0
    
    for word in words:
        # 计算添加单词后的长度
        # (当前单词数 + 空格数)
        if current_line:
            new_length = current_length + len(word) + 1
        else:
            new_length = len(word)
        
        if new_length <= width:
            current_line.append(word)
            current_length = new_length
        else:
            # 对当前行进行两端对齐
            lines.append(justify_line(current_line, width))
            current_line = [word]
            current_length = len(word)
    
    # 处理最后一行（左对齐）
    if current_line:
        lines.append(' '.join(current_line))
    
    return '\n'.join(lines)

def justify_line(words, width):
    """单行两端对齐"""
    if len(words) == 1:
        return words[0].ljust(width)
    
    # 计算总空格数
    total_chars = sum(len(word) for word in words)
    total_spaces = width - total_chars
    gaps = len(words) - 1
    
    # 计算基本空格和额外空格
    base_spaces = total_spaces // gaps
    extra_spaces = total_spaces % gaps
    
    # 构建行
    line = words[0]
    for i in range(1, len(words)):
        # 分配空格
        spaces = base_spaces + (1 if i <= extra_spaces else 0)
        line += ' ' * spaces + words[i]
    
    return line

# 测试
text = "python is an interpreted high-level general-purpose programming language."
print(justify_text(text, 30))
"""
python  is  an interpreted
high-level   general-purpose
programming language.
"""

def align_code_indentation(code):
    """智能对齐代码缩进"""
    lines = code.split('\n')
    indent_level = 0
    indent_size = 4
    result = []
    
    for line in lines:
        stripped = line.strip()
        if not stripped:  # 空行
            result.append('')
            continue
        
        # 计算缩进变化
        if stripped.endswith(':'):
            # 增加缩进层级
            indent_level += 1
        elif stripped.startswith(('return', 'break', 'continue', 'pass')):
            # 减少缩进层级
            indent_level = max(0, indent_level - 1)
        
        # 应用当前缩进
        indent = ' ' * (indent_level * indent_size)
        result.append(indent + stripped)
    
    return '\n'.join(result)

# 测试
code = """
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
"""

print(align_code_indentation(code))
"""
def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)
"""

import timeit

text = "python"
width = 50

def test_ljust():
    return text.ljust(width)

def test_format():
    return format(text, f"<{width}")

def test_fstring():
    return f"{text:<{width}}"

# 性能测试
methods = {
    "str.ljust": test_ljust,
    "format": test_format,
    "f-string": test_fstring
}

results = {}
for name, func in methods.items():
    time = timeit.timeit(func, number=100000)
    results[name] = time

print("100,000次操作耗时:")
for name, time in sorted(results.items(), key=lambda x: x[1]):
    print(f"{name}: {time:.5f}秒")

# 表头居中，数字右对齐，文本左对齐
alignments = ['^', '>', '>', '<']

# 固定宽度对齐关键字段
fmt='%(asctime)s | %(levelname)-8s | %(message)s'

# 大循环中使用str.ljust/rjust
for item in large_list:
    print(item.ljust(20))

# 考虑全角字符宽度
from wcwidth import wcswidth
def real_width(text):
    return wcswidth(text)

class testtextalignment(unittest.testcase):
    def test_table_alignment(self):
        headers = ["id", "name"]
        data = [[1, "alice"], [2, "bob"]]
        table = generate_table(data, headers)
        self.assertin("alice", table)
        self.assertin("|  1  |", table)