python入门基础代码

1、python入门基础代码 #查找index函数的帮助help(str.index) #for循环和break语句from math import sqrtfor i in range(2,101):flag=1k=int(sqrt(i)for j in range(2,k 1):if i%j=0:flag=0breakif(flag):print i#continue语句,满足条件跳出continue后面的语句sumA=0i=1while i=5:sumA =ii =1if i=3:continueprint i=%d,sum=%d%(i,sumA)#循环中的else语句k=5for i in

2、 range(1,10):if k=3:breakelse:print i#自定义函数/素材1-100间素数from math import sqrtdef isprime(x):if x=1:return Falsek=int(sqrt(x)for j in range(2,k 1):if x%j=0:return Falsereturn Truefor i in range(2,101):if isprime(i):print idef f(x,y=True): #默认参数要放在参数列表的最后x and y both correct words or notif y:print x,and

3、 y both correctprint x,is Okf(68)f(68,False)#传递函数def addme2me(x):return(x x)def self(f,y):print f(y)self(addme2me,2.2)#lambda函数my_add=lambda x,y:x ymy_add(5,6)#数据获取与表示f=open(rE:360Downloadsfirstpro.txt,w) #新建一个文件f.write(hello,world) #f为对象，write写入文件f.close()f=open(rE:360Downloadsfirstpro.txt,r) #r代表读

4、出p1=f.read(5) #5代表读出的字节数p2=f.read()print p1,p2f.closef1=open(rE:360Downloadscompanies.txt)cname=f1.readlines()for i in range(0,len(cname):cnamei=str(i 1) cnameif1.closef2=open(rE:360Downloadsscompanies.txt,w)f2.writelines(cname)f2.close()#网络数据获取import urllibr=urllib.urlopen(/)html=r.read#序

5、列#标准类型运算符 applebanana1,2,3!=4,5,6#值比较atuple=(ba,126.4)btuple=atuplebtuple is not atuple#对象身份比较(86.40122.64) and (applebanana)#布尔运算#序列类型运算符week=mondy,tuesday,wednesday,thursday,firday,satuday,sundayprint week1,week-2,n,week1:4,n,week:6,n,week:-1#序列值的序号是从0开始到N-1或者从-1到Napple*3ba in (ba,the boeingcompan

6、y)#序列类型转换工厂函数list(hello,world)#将字符串转成列表tuple(hello,world)#将字符串转成元组#字符串s1=hello abworld!s1 #三引号可以保持里面字符串的原貌s2=rd:pythona.pys2ccode=axp,ba,cat,csco,cvxcprice=86.40,122.64,99.44,23.78,115.91for i in range(5):print %d%8s:%8s %(i,ccodei,cpricei) #%8s指的占8个字符print i get %d%! %32 #两个%会留下一个astr=what do you t

7、hink of this saying no pain,no gain?tempstr=astr.split()1 #为转义字符if tempstr.istitle():print it is title formatelse:print it is not title formatprint tempstr.title()astr=101tx41n#八进制数000代表的字符 t代表横向制表符print astr#列表jscores=9,9,8.5,10,7,8,8,9,8,10ascore=9jscores.sort()jscores.pop() #去掉最高分jscores.pop(0) #

8、去掉最低分jscores.append(ascore) #合并avescore=sum(jscores)/len(jscores)print avescoreweek=monday,tuesday,wednesday,thursday,firdayweekend=saturday,sundayweek.extend(weekend)#extend合并函数for i,j in enumerate(week):#enumerate函数 产生从0开始的序列print i 1,jnumlist=3,11,5,8,16,1numlist.sort(reverse=True) #按逆序排列numlistf

9、ruitlist=apple,banana,pear,lemon,avocadofruitlist.sort(key=len)fruitlist #按字符长度排序#列表解析x*2 for x in range(10)x*2 for x in range(10) if x*22,darray,earray) #where函数def fun(x,y):return (x 1)*(y 1)arr=fromfunction(fun,(9,9) #fromfunction函数arr#ufunc函数能对数组中每个元素进行操作，包括add等函数import numpy as npa=np.arange(1,

10、5)b=np.arange(2,6)np.add(a,b)np.add.accumulate(2,3,8)np.multiply.accumulate(2,3,8)#series#series 类似于一维数组的对象，由数据和索引组成from pandas import Seriesimport pandas as pdaser=pd.Series(1,2.0,a)bser=pd.Series(apple,peach,lemon,index=1,2,3)bser.indexbser.valuesaseraimport numpy as npnp.exp(aser)#series数据对齐data=

11、axp:86,csco:122,ba:94sindex=axp,csco,aaplaser=pd.Series(data,index=sindex)aserpd.isnull(aser)#series的name属性==volumeaser#dataframe表结构#大致可以看成共享一个index的series的集合data=name:wangdachui,linlin,niuyun,pay:4000,5000,6000frame=pd.DataFrame(data)framenameframe.payframe.ix2 #索引所对应的

12、数据#dataframe对象的修改和删除framename=admin #对name下的所有元素进行更改del =no#便捷数据获取#便捷网络数据 雅虎财经from matplotlib.finance import quotes_historical_yahoofrom datetime import dateimport pandas as pdtoday=date.today()start=(today.year-1,today.month,today.day)quotes=quotes_historical_yahoo(AXP,

13、start,today)df=pd.DataFrame(quotes)print df#自然语言工具包NLTKfrom nltk.corpus import gutenbergimport nltkprint gutenberg.fileids()#数据准备from matplotlib.finance import quotes_historical_yahoofrom datetime import dateimport pandas as pdtoday=date.today()start=(today.year-1,today.month,today.day)quotes=quotes

14、_historical_yahoo(AXP,start,today)fields=date,open,close,high,low,volumequotesdf=pd.DataFrame(quotes,columns=fields) #通过columns数据加属性名quotesdf=pd.DataFrame(quotes,index=range(1,len(quotes) 1,columns=fields)print quotesdffrom datetime import datefrom datetime import datetimey=datetime.strftime(x,%Y-%m

15、-%d) #将日期转换成固定格式import pandas as pddates=pd.date_range(,periods=7) #自己创建时间序列dates#数据显示djidf.indexdjidf.columnsdjidf.valuesdjidf.describe#显示数据描述djidf.head(5)#显示前五行数据djidf.tail(5)#数据选择quotesdfu2013-12-02:u2013-12-06 #dataframe可以使用索引选择djidfcodedjidf.loc1:5, #通过loc通过标签选择数据，第一个参数是行标签，第二个参数是列标签djidf.loc:,

16、code,lasttrade #前面这个：需要djidf.loc1:6,0,2 #通过的行位置，列位置选择标签quotesdfquotesdf.index=u2014-01-01quotesdf(quotesdf.index=u2014-01-01)&(quotesdf.close=95)#条件筛选#简单统计预处理djidf.mean(columns=lasttrade)#最近一次成交价的平均值djidfdjidf.lasttrade=120.name#最近一次成交价大于等于120的公司名len(quotesdfquotesdf.closequotesdf.open) #股票涨的天数len(q

17、uotesdf)-131status=np.sign(np.diff(quotesdf.close) #np.diff相邻两天数据的差statusnp.where(status=1.).sizedjidf.sort(columns=lasttrade)27:.name#排序结果列出前三甲的公司名 ，一共是30条记录，所以是27：t=quotesdf(quotesdf.index=u2014-01-01)&(quotesdf.indexlen(t) #统计2014年1月份的股票开盘天数#分组tempdf.groupby(month).count().month #每个月的股票开盘天数tempdf

18、.groupby(month).sum().volume #每个月的股票总成交量g=tempdf.groupby(month)gvolume=gvolumeprint gvolume.sum()#合并#append追加 纵向p=quotesdf:2q=quotesdfu2014-01-01:u2014-01-05p.append(q)#concat连接pieces=tempdf:5,tempdflen(tempdf)-4:pd.concat(pieces)#两个不同逻辑结构的对象能否连接 纵向piece1=quotesdf:3piece2=tempdf:3pd.concat(piece1,piece2,ignore_index=True)#join连接 横向pd.merge(djidf,akdf,on=code)pd.merge.(djidf,akdf,on=code).drop