one useful frequency class is "week of month"starting with wom this enables you to get dates like the third friday of each monthin [ ]rng pd date_range(''''freq='wom- fri'in [ ]list(rngout[ ][traders of us equity options will recognize these dates as the standard dates of monthly expiry shifting (leading and laggingdata "shiftingrefers to moving data backward and forward through time both series and dataframe have shift method for doing naive shifts forward or backwardleaving the index unmodifiedin [ ]ts series(np random randn( )index=pd date_range(''periods= freq=' ')in [ ]ts out[ ]freqm in [ ]ts shift( out[ ]nan nan freqm in [ ]ts shift(- out[ ] nan nan freqm common use of shift is computing percent changes in time series or multiple time series as dataframe columns this is expressed as ts ts shift( because naive shifts leave the index unmodifiedsome data is discarded thus if the frequency is knownit can be passed to shift to advance the timestamps instead of simply the datain [ ]ts shift( freq=' 'out[ ] freqm date rangesfrequenciesand shifting www it-ebooks info