python 大数字添加千分符

def NumberToStr(num, flag=True):
try:
if flag:
num = int(num)
else:
num = float(num)
except:
return num
if(type(float(1.1))==type(num)):
str_num="%.2f"%num
elif (type(int(1))==type(num)):
str_num=str(num)
else:
return num
left_len=length=len(str_num)
right_len=0
dot_cnt=str_num.count('.',0,length)
if(dot_cnt!=0):#小数
left_len=str_num.index('.',0,length)
right_len=length-left_len
cnt=left_len//3
result=[]
end=left_len
while(cnt>0):
result.append(str_num[end-3:end])
end-=3
cnt-=1
result.append(str_num[:end])
result.reverse()
result_str=','.join(result)
result_str+=str_num[left_len:]
if(result_str[0]==','):
return result_str[1:]
else:
return result_str