Python日常小知识

一：python列表中的所有值转换为字符串，以及列表拼接成一个字符串

> ls1 = ['a', 1, 'b', 2] 
> ls2 = [str(i) for i in ls1]
> ls2 ['a', '1', 'b', '2'] 
>ls3 = ''.join(ls2) 
> ls3 'a1b2'

二：字符串转换

#字符串转为元组，返回：(1, 2, 3)
print tuple(eval("(1,2,3)"))
#字符串转为列表，返回：[1, 2, 3]
print list(eval("(1,2,3)"))
#字符串转为字典，返回：<type 'dict'>
print type(eval("{'name':'ljq', 'age':24}"))

三：创建文件并按行写入数据

with open("%s\sitemap%d.txt" % (self.path,file_num), "a") as f:
    for i in url_list:
        u  = str(i) + '\n'
        f.writelines(u)
    f.close()

四：Python调用API接口的几种方式

方式一：
import urllib2, urllib
github_url = 'https://api.github.com/user/repos'
password_manager = urllib2.HTTPPasswordMgrWithDefaultRealm()
password_manager.add_password(None, github_url, 'user', '***')
auth = urllib2.HTTPBasicAuthHandler(password_manager) # create an authentication handler
opener = urllib2.build_opener(auth) # create an opener with the authentication handler
urllib2.install_opener(opener) # install the opener...
request = urllib2.Request(github_url, urllib.urlencode({'name':'Test repo', 'description': 'Some test repository'})) # Manual encoding required
handler = urllib2.urlopen(request)
print handler.read()

方式二：
import urllib, httplib2
github_url = ""
h = httplib2.Http(".cache")
h.add_credentials("user", "******")
data = urllib.urlencode({"name":"test"})
resp, content = h.request(github_url, "POST", data)
print content

方式三：
import pycurl, json
github_url = ""
user_pwd = "user:*****"
data = json.dumps({"name": "test_repo", "description": "Some test repo"})
c = pycurl.Curl()
c.setopt(pycurl.URL, github_url)
c.setopt(pycurl.USERPWD, user_pwd)
c.setopt(pycurl.POST, 1)
c.setopt(pycurl.POSTFIELDS, data)
c.perform()

方式四：
import requests, json
github_url =""
data = json.dumps({'name':'test', 'description':'some test repo'})
r = requests.post(github_url, data, auth=('user', '*****'))
print r.json
以上几种方式都可以调用API来执行动作，但requests这种方式代码最简洁，最清晰，建议采用。

例子：
import requests
reqs = requests.session()
reqs.keep_alive = False
import json
url = "http://127.0.0.1:9999/download/login" #接口地址
data = {"user": "****", "password": "*****"}
r = requests.post(url, data=data)
print r.text
print type(r.text)
print json.loads(r.text)["user_id"]  

五：将list列表里的数据按行写入到txt文件

with open(file_num, "w") as f:
    for ip in url_list:
        f.write(ip)
        f.write('\n')
    f.close()

六：Python判断字符串是否为字母或者数字

严格解析：有除了数字或者字母外的符号（空格，分号,etc.）都会False
isalnum()必须是数字和字母的混合
isalpha()不区分大小写
str_1 = "123"
str_2 = "Abc"
str_3 = "123Abc"

#用isdigit函数判断是否数字
print(str_1.isdigit())
Ture
print(str_2.isdigit())
False
print(str_3.isdigit())
False

#用isalpha判断是否字母
print(str_1.isalpha())    
False
print(str_2.isalpha())
Ture    
print(str_3.isalpha())    
False

#isalnum判断是否数字和字母的组合
print(str_1.isalnum())    
Ture
print(str_2.isalnum())
Ture
print(str_1.isalnum())    
Ture

未完待续。。。

（欢迎加入Python交流群：930353061。人生苦短，我用python！！！）