true true see table - for reference on these methods table - uniquevalue countsand binning methods method description isin compute boolean array indicating whether each series value is contained in the passed sequence of values unique compute array of unique values in seriesreturned in the order observed value_counts return series containing unique values as its index and frequencies as its valuesordered count in descending order in some casesyou may want to compute histogram on multiple related columns in dataframe here' an examplein [ ]data dataframe({'qu '[ ]'qu '[ ]'qu '[ ]}in [ ]data out[ ]qu qu qu passing pandas value_counts to this dataframe' apply function givesin [ ]result data apply(pd value_countsfillna( in [ ]result out[ ]qu qu qu handling missing data missing data is common in most data analysis applications one of the goals in designing pandas was to make working with missing data as painless as possible for exampleall of the descriptive statistics on pandas objects exclude missing data as you've seen earlier in the getting started with pandas www it-ebooks info