I want to calculate Centered Moving average of a set of Data . Example Input format : quarter | sales Q1'11 | 9 Q2'11 | 8 Q3'11 | 9 Q4'11 | 12 Q1'12 | 9 Q2'12 | 12 Q3'12 | 9 Q4'12 | 10 Mathematical Representation of data and calculation of Moving average and then centered moving average Period Value MA Centered 1 9 1.5 2 8 2.5 9.5 3 9 9.5 3.5 9.5 4 12 10.0 4.5 10.5 5 9 10.750 5.5 11.0 6 12 6.5 7 9 I am stuck with the implementation of RecordReader which will provide mapper sales value of a year i.e. of four quarter. The RecordReader Problem Question Thread Thanks