python - Pandas Dataframe label selection -

-

can tell me why df['2005-5-31'] trigger keyerror exception?

rng = pd.date_range('2005', '2012', freq='m') df = pd.dataframe(randn(len(rng), 3), rng, ['x', 'y', 'z']) df.head()  # works df.ix['2005-5-31'] df['2005-5-31':'2005-5-31']  # gives keyerror: u'no item named 2005-5-31' df['2005-5-31']

follow code using df['2000-01-01'] works.

#multiple rows on single date rng = pd.date_range('2000-01-01', '2000-01-3', freq='8h') df = pd.dataframe(randn(len(rng), 3), rng, ['x', 'y', 'z'])  # works df['2000-01-01']                             x    y   z 2000-01-01 00:00:00 -0.227981    1.927932   -0.518947 2000-01-01 08:00:00  0.486063   -1.255186    0.375075 2000-01-01 16:00:00 -2.313950    0.654384    1.111493

df['2005-5-31'] returns column named: 2005-5-31. columns named x,y,z. , because don't have date column, giving error!

now .ix[] method works because takes 2 inputs, first input being row index. have row index '2005-5-31' works!


Comments

Post a Comment

Popular posts from this blog

java - Jmockit String final length method mocking Issue -

-
using jmockit 1.2 jar, trying mock string's length method getting unexpected invocation exception: failed: test java.lang.illegalstateexception: missing invocation mocked type @ point; please make sure such invocations appear after declaration of suitable mock field or parameter @ stringdemo.testa$1.<init>(testa.java:17) @ stringdemo.testa.test(testa.java:13) i using testng: @test public void test() throws exception { new expectations() { @mocked("length") string astring; { astring.length(); result = 2; } }; system.out.println(a.showa("test")); } } actual class a: public class { public static int showa(string str){ int a= str.length(); return a; } } this wrong way of recording expected results. shouldn't mock , record string's length() method, record showa() instead. here solution @suppresswarnings("unused...
Read more

What is the difference between data design and data model(ERD) -

-
i have google question , find answer in day. know, data design many many table have list column,and mark pk , fk. why er-diagram have find this? data design process of designing database. main output of data design detailed logical data model of database. some people data design includes of needed logical , physical design choices , physical storage parameters needed generate design in data definition language. technically, database analysis, database analysts (dbas) trained do. while person can both data design , database analysis, these 2 different tasks. data design models data. database analysis takes model , applies 1 or more database engines (relational, hierarchical, nosql). a logical data model 1 of main outputs of data design. data model represented entity relationship diagram, or er diagram.
Read more

ios - Can NSManagedObject conform to NSCoding -

-
i need transfer single object across device. right converting nsmanagedobject dictionary , archiving , sending nsdata. upon receiving unarchiving it. transfer nsmanagedobject archiving , unarchiving instead of creating intermediate data object. @interface test : nsmanagedobject<nscoding> @property (nonatomic, retain) nsstring * title; @end @implementation test @dynamic title; - (id)initwithcoder:(nscoder *)coder { self = [super init]; if (self) { self.title = [coder decodeobjectforkey:@"title"]; //<crash } return self; } - (void)encodewithcoder:(nscoder *)coder { [coder encodeobject:self.title forkey:@"title"]; } @end nsdata *archivedobjects = [nskeyedarchiver archiveddatawithrootobject:testobj]; nsdata *objectsdata = archivedobjects; if ([objectsdata length] > 0) { nsarray *objects = [nskeyedunarchiver unarchiveobjectwithdata:objectsdata]; } the problem above code is. crashes @ self.title in initwithcoder sa...
Read more