structuresin [ ]index pd index(np arange( )in [ ]obj series([ - ]index=indexin [ ]obj index is index out[ ]true table - has list of built-in index classes in the library with some development effortindex can even be subclassed to implement specialized axis indexing functionality many users will not need to know much about index objectsbut they're nonetheless an important part of pandas' data model table - main index objects in pandas class description index the most general index objectrepresenting axis labels in numpy array of python objects int index specialized index for integer values multiindex "hierarchicalindex object representing multiple levels of indexing on single axis can be thought of as similar to an array of tuples datetimeindex stores nanosecond timestamps (represented using numpy' datetime dtypeperiodindex specialized index for period data (timespansin addition to being array-likean index also functions as fixed-size setin [ ]frame out[ ]state nevada ohio year nan in [ ]'ohioin frame columns out[ ]true in [ ] in frame index out[ ]false each index has number of methods and properties for set logic and answering other common questions about the data it contains these are summarized in table - introduction to pandas data structures www it-ebooks info