python常见操作

1、数组for初始化

Y=[ 2.5,3.51,4.45,5.52,6.47,7.51]
X = [x+1 for x in range(len(Y))]

2、字符串时间加减

A="2007-07-06"
B="2007-07-26"
def getDay_num(start,end):
        x = datetime.datetime.strptime(end, '%Y-%m-%d')
        x2 = datetime.datetime.strptime(start, '%Y-%m-%d')
        v = x-x2
        return v.days
print getDay_num(A,B)

3、词典值为空判断
加上跟踪快速捕获错误

dict = {}
dict["a"]="bbbbbbbbbb"
print dict['a']
if not dict.has_key('b'):
        print "addddddasdfdsaf"

4、python打印异常信息两种方式
1）、直接打印

try:

    # your code
 except KeyboardInterrupt:

    print("quit")

except Exception as ex:
     print("出现如下异常%s"%ex)

2）、用traceback模块打印
点击(此处)折叠或打开

import traceback
try:
    2/0
except Exception as e:
    traceback.print_exc()

5、日志错误
加上跟踪快速捕获错误

import logging
import logging.handlers
def LOG(str):

        logger = logging.getLogger("fetchlogs") # 获取名为tst的logger
        if not logger.handlers:
                ISOTIMEFORMAT='%Y%m%d'
                LOG_NAME= './fetchlogs/log_atr'
                LOG_NAME = LOG_NAME+ time.strftime( ISOTIMEFORMAT, time.localtime())
                LOG_NAME = LOG_NAME + ".txt"

                handler = logging.handlers.RotatingFileHandler(LOG_NAME, maxBytes = 5*1024*1024, backupCount = 5)
                fmt = '%(asctime)s - %(filename)s:%(lineno)s - %(name)s - %(message)s'

                formatter = logging.Formatter(fmt) # 实例化formatter
                handler.setFormatter(formatter) # 为handler添加formatter

                logger.addHandler(handler) # 为logger添加handler
                logger.setLevel(logging.DEBUG)


        logger.info(str)

def Log_exception(str):

        logger = logging.getLogger("fetchlogserr") # 获取名为tst的logger
        if not logger.handlers:
                ISOTIMEFORMAT='%Y%m%d'
                LOG_NAME= './fetchlogs/log_atr_err'
                LOG_NAME = LOG_NAME+ time.strftime( ISOTIMEFORMAT, time.localtime())
                LOG_NAME = LOG_NAME + ".txt"

                handler = logging.handlers.RotatingFileHandler(LOG_NAME, maxBytes = 5*1024*1024, backupCount = 5)
                fmt = '%(asctime)s - %(filename)s:%(lineno)s - %(name)s - %(message)s'

                formatter = logging.Formatter(fmt) # 实例化formatter
                handler.setFormatter(formatter) # 为handler添加formatter

                logger.addHandler(handler) # 为logger添加handler
                logger.setLevel(logging.DEBUG)


        logger.exception(str)

6、数组降维度

#reshape函数当参数只有一个-1时表示将数组降为一维

np.ravel 降为一维数组

import numpy as np
t = ar(range(10),dtype = 'float32')
print t

t2= t.reshape((10,1))
print t2
t3=t2.reshape(-1)
print t3

print np.ravel(t2)