[R] average of y at each level of x?

[kjetil@entelnet.bo]

On 7 Nov 2003 at 9:47, Bill Simpson wrote:

Since your y is 0-1 the following works:

tapply(x, y ,mean)

aggregate(x, y, mean)
gives the output in a different format.

Kjetil Halvorsen

> I have x,y data and would like to compute the average of y at each level 
> of x.
> 
> > x
>  [1] 0.006110 0.007027 0.007027 0.007027 0.008081 0.008081 0.008081 0.008081
>  [9] 0.008081 0.008081 0.008081 0.009293 0.009293 0.009293 0.009293 0.009293
> [17] 0.009293 0.009293 0.009293 0.010686 0.010686 0.010686 0.010686 0.010686
> [25] 0.010686 0.010686 0.010686 0.010686 0.010686 0.012289 0.012289 0.012289
> [33] 0.012289 0.012289 0.012289 0.012289 0.012289 0.012289 0.012289 0.012289
> [41] 0.012289 0.012289 0.014133 0.014133 0.014133 0.014133 0.016253 0.018691
> [49] 0.021494 0.024718 0.028426 0.032690 0.037594 0.043233 0.049718 0.057175
> [57] 0.065752 0.075614 0.086957 0.100000
> 
> > y
>  [1] 0 0 1 0 0 1 0 1 1 0 1 1 1 0 1 0 1 0 1 0 1 1 0 1 1 0 1 0 1 1 1 0 1 1 1 1 1 1
> [39] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
> 
> > table(x,y)
>           y
> x          0  1 
>   0.00611   1  0
>   0.007027  2  1
>   0.008081  3  4
>   0.009293  3  5
>   0.010686  4  6
>   0.012289  1 12
>   0.014133  0  4
>   0.016253  0  1
>   0.018691  0  1
>   0.021494  0  1
>   0.024718  0  1
>   0.028426  0  1
>   0.03269   0  1
>   0.037594  0  1
>   0.043233  0  1
>   0.049718  0  1
>   0.057175  0  1
>   0.065752  0  1
>   0.075614  0  1
>   0.086957  0  1
>   0.1       0  1
> 
> I would like to compute p = count1/(count0 +count1). For example, for
> x=0.012289, p= 12/(1+12)= 0.923077. Please tell me how to do it. Maybe 
> there is a better way to do this without going through table().
> 
> Thanks very much for any help.
> 
> Bill Simpson
> 
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