UNIX for Dummies Questions & Answers

Hi

I have 100 xy graphs and need to average these together in a line by line fashion. The value of the x axis are the same. y differs e.g. taking only 2 graphs:

graph 1

Code:

x    y
1    3 
2    5
3    7 
4    9
5    11

graph 2

Code:

x    y
1    4
2    6
3    10 
4    12
5    15

The average graph which I need to calculate would be

Code:

x    y
1    3.5 
2    5.5
3    8.5 
4    10.5
5    13

in this format.
All the examples I have found using awk calculate the average of the entire column which isn't what I need
Can anyone point me in the right direction?

Thanks

Moderator's Comments:

Use code tags please, ty.

Hi

Code:

[root@gpr ~]# cat a1
1 3
2 5
3 7
4 9
5 11
[root@gpr ~]# cat a2
1 4
2 6
3 10
4 12
5 15
[root@gpr ~]# paste a1 a2  | awk '{print $1, ($2+$4)/2}'
1 3.5
2 5.5
3 8.5
4 10.5
5 13
[root@gpr ~]#

Guru.

great thanks