Python pandas

pandas 有本身的格式，總結起來

有如下共通點

1.函數，好比格式的series,DataFrame，或者numpy後面跟的數據函數，例如exp,arange,後面確定是跟的()
2.數據,series,frame,dict,指定行列，賦值調取數據，後面跟的是【】
3.series 格式比較固定，一部分是index,另外一部分是value.obj2= Series([4,7,-5,3],index=['d','b','a','c'])
4.frame 一樣，分三部分， data,columns,index,
frame2= DataFrame(data,columns=['year','state','pop','debt'],index=['one','two','three','four','five'])
沒有數據的都用NAN補充
5.通常的基本的數據層級爲pop={'Nevada':{2001:2.4,2002:2.9},'Ohio':{2000:1.5,2001:1.7,2002:3.6}} {E:{A：B,C:D},F:{A:B,C:D}}
6.轉置 frame3.T
7.獲取data.
'''get value by columns
frame2['state']
'''get value by index
frame2.ix['three']

from pandas import Series,DataFrameimport pandas as pd'''indexobj2= Series([4,7,-5,3],index=['d','b','a','c'])obj2.valuesobj2.indexobj2['a']obj2['c']obj2['d'] = 6obj2[['c','d','a']]obj2obj2[obj2>0]obj2*2import numpy as npnp.exp(obj2)''' dict'b' in obj2'e' in obj2data = {'Ohio':35000,'Texas':71000,'Oregon':16000,'Utah':5000}obj3 = Series(data)obj3'''passing a dictstates = ['California','Ohio','Oregon','Texas']obj4 = Series(data,index=states)'''missing datapd.isnull(obj4)pd.notnull(obj4)'''auto align indexobj3obj4obj3+obj4'''name and renameobj4.name = 'population'obj4.index.name = 'state'obj4obj2.index=['Bob','Helen','Jeff','Ryan']'''dataframe,by default by name orderdata={'state':['Ohio','Ohio','Ohio','Nevada','Nevada'],'year':[2000,2001,2002,2001,2002],'pop':[1.5,1.7,3.6,2.4,2.9]}frame = DataFrame(data)'''order by special orderDataFrame(data,columns =['year','state','pop'])''' add one column and indexframe2= DataFrame(data,columns=['year','state','pop','debt'],index=['one','two','three','four','five'])frame2.columns'''get value by columnsframe2['state']'''get value by indexframe2.ix['three']'''assignment by indexframe2['debt'] = 16.5frame2['debt'] = np.arange(5.)val = Series([-1.2,-1.5,-1.7],index=['two','four','five'])frame2['debt'] = val'''del columnsframe2['eastern'] = frame2.state == 'Ohio'del frame2['eastern']'''nest dictpop={'Nevada':{2001:2.4,2002:2.9},'Ohio':{2000:1.5,2001:1.7,2002:3.6}}frame3=DataFrame(pop)'''transpose the frameframe3.T'''index changes different with seriesDataFrame(pop,index=[2001,2002,2003])'''dataframe get valuepdata = {'Ohio':frame3['Ohio'][:-1],          'Nevada':frame3['Nevada'][:2]}DataFrame(pdata)'''data frame index and column name attributeframe3.index.name = 'year';frame3.columns.name = 'state'frame3