Python字符串处理及实现字符串拼接的示例解析

# 单双引号通用
msg = "Hello 数据科学家！"
path = r'C:\new_folder'  # 原始字符串避免转义
# 切片操作 [start:end:step]
text = "Python超实用"
print(text[2:5])     # tho
print(text[::-1])    # 用实超nohtyP

names = ["张伟", "李娜", "王阳"]
# 传统方式（性能低）
full_str = names[0] + "," + names[1] + "," + names[2]
# 高效方式
print(",".join(names))  # 张伟,李娜,王阳
# 现代方式（推荐）
print(f"获奖者：{names[0]}、{names[1]}、{names[2]}")

# 拆分CSV数据
csv_data = "ID,Name,Salary\n101,张三,15000"
rows = csv_data.split('\n')
for row in rows:
    cols = row.split(',')
    print(cols)
# 重组URL路径
folders = ['img','2024','logo.png']
print('/'.join(folders))  # img/2024/logo.png

log = "ERROR: File not found [code:404]"
# 定位关键信息
print(log.find("404"))    # 28
print("ERROR" in log)     # True
# 敏感信息脱敏
secure_log = log.replace("404", "XXX")
print(secure_log)  # ERROR: File not found [code:XXX]

# 1. %格式化（经典）
print("温度：%.1f°C" % 23.456)  # 温度：23.5°C
# 2. str.format()（灵活）
print("坐标：({x},{y})".format(x=120, y=89))
# 3. f-string（推荐）
name = "Alice"
print(f"欢迎{name.upper()}！积分：{1000*1.2:.0f}")

raw_text = "  Python数据分析  \t\n"

# 去空格
clean_text = raw_text.strip()  
print(clean_text)  # "Python数据分析"

# 大小写转换
print(clean_text.upper())  # PYTHON数据分析
print(clean_text.lower())  # python数据分析

# 首字母大写
print("hello world".title())  # Hello World

def clean_text_data(text):
    """文本清洗标准化流程"""
    # 1. 去除首尾空白
    text = text.strip()  
    # 2. 转换为小写
    text = text.lower()  
    # 3. 替换特殊字符
    text = text.replace('$', 'USD').replace('¥', 'CNY')
    # 4. 分割重组
    words = text.split()
    return ' '.join(words[:5])  # 保留前5个词
raw_data = "  $19.99 限时优惠 买一送一  "
print(clean_text_data(raw_data))  
# 输出：usd19.99 限时优惠 买一送一

>>> 'Hello' + ' ' + 'World' + '!'
'Hello World!'

>>> strlist = ['Hello', ' ', 'World', '!']
>>> ''.join(strlist)
'Hello World!'

>>> '{} {}!'.format('Hello', 'World')
'Hello World!'

>>> '%s %s!' % ('Hello', 'World')
'Hello World!'

>>> (
...     'Hello'
...     ' '
...     'World'
...     '!'
... )
'Hello World!'

>>> from string import Template
>>> s = Template('${s1} ${s2}!') 
>>> s.safe_substitute(s1='Hello',s2='World')
'Hello World!'

>>> from string import Template
>>> s = Template('${s1} ${s2} ${s3}!') 
>>> s.safe_substitute(s1='Hello',s2='World')
'Hello World ${s3}!'

>>> s1 = 'Hello'
>>> s2 = 'World'
>>> f'{s1} {s2}!'
'Hello World!'

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>>> def power(x):
...     return x*x
... 
>>> x = 5
>>> f'{x} * {x} = {power(x)}'
'5 * 5 = 25'