python实现list元素按关键字相加减的方法

# coding=utf-8

# 两个list按关键字相加或相减

defListAdd(list1, list2, bAdd=True):

  ifbAdd==False:

    list2=[(k,-v)for(k, v)inlist2]

  d={}

  list0=list1+list2

  for(k, v)inlist0:

    d.setdefault(k,0)  # 设置字典元素初始值

    d[k]+=v       # 对字典中的元素按关键字相加

  ret=list(d.items())   # 字典转换成list

  ret=sorted(ret)     # 对list排序

  returnret

if__name__=='__main__':

  a=[("s1",10), ("s2",13), ("s3",25), ("s7",30)]

  b=[("s1",22), ("s3",16), ("s10",8)]

  print("a=", a)

  print("b=", b)

  ret1=ListAdd(a, b)   # ret1 = a + b

  print("ret1=", ret1)

  ret2=ListAdd(a, b,False)# ret2 = a - b

  print("ret2=", ret2)

E:\Program\Python>del.py

a=[('s1',10), ('s2',13), ('s3',25), ('s7',30)]

b=[('s1',22), ('s3',16), ('s10',8)]

ret1=[('s1',32), ('s10',8), ('s2',13), ('s3',41), ('s7',30)]

ret2=[('s1',-12), ('s10',-8), ('s2',13), ('s3',9), ('s7',30)]

//1、基本应用

$now= Carbon::now();         //2016-11-03 14:13:16

$today= Carbon::today();       //2016-11-03 00:00:00

$tomorrow= Carbon::tomorrow();    //2016-11-04 00:00:00

$yesterday= Carbon::yesterday();   //2016-11-02 00:00:00

//2、判断是否是某一天(2016-11-03（周四）举例)

$now= Carbon::now();

var_dump($now->isWeekend());//false 因为周四不是周末

var_dump($now->isWeekday());//true 因为周四是工作日

var_dump($now->isThursday());//true 因为今天是周四

$now->isToday();

$now->isTomorrow();

$now->isFuture();

$now->isPast();

//3、创建某一天的carbon对象并且进行加减计算

$date= Carbon::create(2016, 12, 25, 0, 0, 0);//2016-12-25 00:00:00

$next_year=$date->addYears(2);//2018-12-25 00:00:00

$past_year=$date->subYears(2);//2014-12-25 00:00:00

$next_month=$date->addMonths(2);//2017-02-25 00:00:00

$past_month=$date->subMonths(2);//2016-10-25 00:00:00

$next_day=$date->addDays(2);//2016-12-27 00:00:00

$past_day=$date->subDays(2);//2016-12-23 00:00:00

...更有addWeekdays()、addWeeks()、addHours()等方法

//4、将carbon对象转换成string类型

$dt= Carbon::create(1975, 12, 25, 14, 15, 16);

echo$dt->toDateString();            // 1975-12-25

echo$dt->toFormattedDateString();        // Dec 25, 1975

echo$dt->toTimeString();            // 14:15:16

echo$dt->toDateTimeString();          // 1975-12-25 14:15:16

echo$dt->toDayDateTimeString();         // Thu, Dec 25, 1975 2:15 PM

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php composer-setup.php

php -r"unlink('composer-setup.php');"