title: TypeError: Index does not support mutable operations - iterating over range of dates
body: <p>I have two column dates(type objects which has worked for rest of my code), and am trying to split the range between these dates into two/more financial years, sum them and multiply this with day rate to get revenue and iterate this through every row in my dataframe.</p>
  
  <p>I am working out revenue per person/row and have calculated this by iterating through itterows and calculating revenue = rate*number of days. Now as and extension of that i've got the range of two date columns, i want to sum the dates before and after the tax year and multiply this with rate per day. 
  ive tried to include this into my iteration
      day_range[i] =  pd.bdate_range(start, end)
  and it gives the type error Index does not support mutable operations. Complete code works when i dont add the [i] for all columns except th elast two lines below.
  Ive also tried 
      day_range.date[i] and 
      day_range.datetime index][i]
  and this gives me IndexError: index 2 is out of bounds for axis 0 with size 1
  and TypeError: 'DatetimeIndex' object cannot be interpreted as an integer
  respectively. All columns populate correctly except for the last two lines below which are my column name assignments</p>
  
  <pre><code>financialYear0 = []
  financialYear1= []
  dateString0 = []  
  dateString1 = []
  i = 0
  
  for i, row in df.iterrows():
      start = pd.to_datetime(df['Start_'][i])
      end = pd.to_datetime(df['End_'][i])
      holidays = df['Holidays'][i]       
      df['Project_Days'][i] = workdays(start, end, holidays)
      rev[i] = day[i] * rate[i]
      rev[i] = rev[i]*df['Percentage'][i]//100
      day_range.datetimeindex =  pd.bdate_range(start, end)
  
      for day_ in range(day_range.datetimeindex):
          date_str = datetime.datetime(day_.year, day_.month, day_.day, 0, 
  0)
          date_str = day_.strftime('%m, %d, %Y')
          date_ = datetime.datetime.strptime(date_str, "%m, %d, 
  %Y").date()
          year_of_date=date_.year
          #initialize the current financial year start date
          financial_year_start_date = datetime.datetime.strptime("04, 01, 
  " + 
          str(year_of_date), "%m, %d, %Y").date()
          #change back to string
  
          if date_&lt;financial_year_start_date:
              str_date0 = datetime.datetime(date_.year, date_.month, 
  date_.day, 
           0, 0)
              str_date0 = date_.strftime('%d, %m, %Y')
              dateString0.append(str_date0)
          else: 
              str_date1 = datetime.datetime(date_.year, date_.month, 
  date_.day, 
           0, 0)
              str_date1 = date_.strftime('%d, %m, %Y')
              dateString1.append(str_date1)
  
      num_string = len(dateString0)
      num_string1 = len(dateString1)
      financialYear0[i] = num_string * rate[i]
      financialYear1[i] = num_string1 * rate[i]   
  </code></pre>
  
  <p>my last two lines are giving incorrect results for second to last rows and correct for the first row. I suspect that it goes wrong when i trying to mak my day_range iterable by adding [i]</p>