How can spaces in dataframe column names be replaced with "_"? ['join_date' 'fiscal_quarter' 'fiscal_year' 'primary_channel' 'secondary_channel' 'customer_count' 'new_members' 'revisit_next_day' 'revisit_14_day' 'demand_1yr' 'revisit_next_day_rate' 'revisit_14_day_rate' 'demand_1yr_per_new_member' u'ch_Ad Network' u'ch_Affiliate' u'ch_Branded SEM' u'ch_DSP' u'ch_Daily Email' u'ch_Daily Messaging' u'ch_Direct' u'ch_Direct Publisher' u'ch_Email' u'ch_Feeds' u'ch_Native' u'ch_Non-Branded SEM' u'ch_Organic Search' u'ch_Paid Social' u'ch_Site' u'ch_Special Email' u'ch_Television' u'ch_Trigger Email' u'ch_UNMAPPED' u'ch_Unpaid Social' u'quarter_Q2' u'quarter_Q3' u'quarter_Q4'] Continue reading...
