how to find the week which secured highest sales ..using map and reducer : how to find the week which secured highest sales ..using map and reducer
this is my sample .csv file


how can i find the week that has the highest sale 

train.csv


Store,Dept,Date,Weekly_Sales,IsHoliday

1,1,2010-02-05,24924.5,FALSE

1,1,2010-02-12,46039.49,TRUE
1,1,2010-02-19,41595.55,FALSE
1,1,2010-02-26,19403.54,FALSE
1,1,2010-03-05,21827.9,FALSE
1,1,2010-03-12,21043.39,FALSE
1,1,2010-03-19,22136.64,FALSE
1,1,2010-03-26,26229.21,FALSE
1,1,2010-04-02,57258.43,FALSE




thanks in Advance