110 lines
2.8 KiB
Markdown
110 lines
2.8 KiB
Markdown
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# Python 常用功能
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## 一、python高频常用
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**1.1 Python简单main框架**
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```python
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import os
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def func():
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print('func')
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if __name__ =="__main__":
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# 遍历文件夹所有文件
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func()
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```
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**1.2 文件夹遍历**
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```python
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import os
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def get_filelist(path):
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Filelist = []
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for home, dirs, files in os.walk(path):
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for filename in files:
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# 完整路径文件名列表
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Filelist.append(os.path.join(home, filename))
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# 文件名列表，只包含文件名
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#Filelist.append(filename)
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return Filelist
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# 获取文件夹文件路径
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Filelist = get_filelist('F:/data_all_apps/')
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# 打印文件完整路径
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for file in Filelist :
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print(file)
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```
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**1.3 保留两位小数**
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```python
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# 方法一：格式化字符串
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a = 12.345
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b = 12.122276
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print("%.2f %.2f" % (a,b))
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# 方法二：round函数
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a = 12.44476
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print(round(a,2))
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```
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**1.4 python格式化字符串**
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```python
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str = "hello"
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print("this is a string: %s" % str)
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print("this is a string: %s, %s" % (str, str))
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idx = 2.66788
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print("this %.2f is a string: %s, %s" % (idx, str, str))
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```
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其他丰富样例：
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```python
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first = "持续学习"
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second = "持续开发"
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slogan = first + second
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print(slogan)
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banner = "*" * 16
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print(banner)
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slice = slogan[2:4]
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print(slice)
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print(""""学习" in slogan ： %s""" % ("学习" in slogan))
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print(""""不学习" not in slogan ： %s""" % ("不学习" not in slogan))
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print(r"""打印\n换行被当做普通字符输出了！""")
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# 以上我们都可以看到%，很多次代码都有说到这个，但是并没有过多解释
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print("%s" % slogan) # 最常用了%s 格式化字符串
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# print("%c"%'ccc')#TypeError: %c requires int or char
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print("%c" % 'c') # %c 通常用来强制检测待输出的字符串必须长度为1
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print("%c" % '雷') # %c 通常用来强制检测待输出的字符串必须长度为1
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number = 102.40101
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print("%%i 符号整数 %i" % number)
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print("%%i 符号整数：%i" % -number)
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print("%%d 符号整数 %d" % number)
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print("%%d 符号整数 %d" % -number)
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print("%%u 无符号整数：%u" % number)
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print("%%u 无符号整数：%u" % -number)
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#print("八进制 %o" % number)
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print("%%o 八进制 %o" % 102)
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print("%%x16进制 %x" % 102)
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#print("16进制 %X" % 102)
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print("%%e 自然常数 e进制： %e" % number)
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#print("%E" % number)
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print("%%f 浮点数 %f" % number)
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#保证显示6微有效数字的前提下，灵活的选择小数方式，或者科学计数法
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print("%%g 灵活的有效显示：%g" % number)
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#print("%G" % number)
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#保证显示6微有效数字的前提下，灵活的选择小数方式，或者科学计数法
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print("%%g 灵活的有效显示：%g" % (number*10001))
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#下面两种写法需要注意执行顺序
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#print("%g" % number*10001) #注意这种写法
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#print("%g" % number**10) #注意这种写法
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```
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1.5 系统暂停
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```python
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os.system('pause')
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```
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