记录python一些技巧

def to_unicode(unicode_or_str):
    if isinstance(unicode_or_str,str):
        value = unicode_or_str.decode('utf-8')
    else:
        value = unicode_or_str
    return value

def to_str(unicode_or_str):
    if isinstance(unicode_or_str,unicode):
        value = unicode_or_str.encode('utf-8')
    else:
        value = unicode_or_str
    return

import os
from PyPDF2 import PdfFileReader,PdfFileMerger
files_dir = 'e:\\pdf'
pdf_files = [f for f in os.listdir(files_dir) if f.endswith('pdf')]
merger = PdfFileMerger()
for filename in pdf_files:
    merger.append(PdfFileReader(os.path.join(file_dir,filename),'rb'))
merger.write(os.path.join(files_dir,'merged_full.pdf'))

files = os.listdir('.')
# [:-4]=.后缀
files.sort(key = lambda x:int(x[:-4]))

import shutil
shutil.rmtree(ur'E:\XX\中文目录)
# 在路径前面加u代表对字符串进行unicode编码

n = '123'
s = n.zfill(5)
print s
>>>
'00123'

n = '-123'
s = n.zfill(5)
print s
>>>
'-0123'

# 对于纯数字，可以通过格式化的方式来补0
n = 123
s = '%05d' % n
print s
>>>
'00123'