in [ ]labels out[ ]categorical:contb_receipt_amt array([( ]( ]( ]( ]( ]( ]]dtype=objectlevels ( )array([( ]( ]( ]( ]( ]( ]( ]( ]]dtype=objectwe can then group the data for obama and romney by name and bin label to get histogram by donation sizein [ ]grouped fec_mrbo groupby(['cand_nm'labels]in [ ]grouped size(unstack( out[ ]cand_nm obamabarack contb_receipt_amt ( ( ( ( ( ( ( ( romneymitt nan nan this data shows that obama has received significantly larger number of small donations than romney you can also sum the contribution amounts and normalize within buckets to visualize percentage of total donations of each size by candidatein [ ]bucket_sums grouped contb_receipt_amt sum(unstack( in [ ]bucket_sums out[ ]cand_nm obamabarack contb_receipt_amt ( ( ( ( ( ( ( ( romneymitt nan nan in [ ]normed_sums bucket_sums div(bucket_sums sum(axis= )axis= in [ ]normed_sums out[ ]cand_nm obamabarack contb_receipt_amt ( ( ( romneymitt data aggregation and group operations www it-ebooks info