Ibtesam,
you are using the wrong mailing list, you should be using R-help, not
the GUI list.
Anyway, if you execute "print(z,digits=20)", you see that the reason for
your different ranks is in numerical accuracy of representations of the
numbers.
Regards,
Ulrike
ibtesam al_sagaf schrieb:
Dear all
I'm Ibtesam.
I use R program in my studded.
I have been seeing problem in rank function. It works as a wrong way from
vector to other.
I run this code many times, in every time I obtained this result;
1- When I enter this data vector manually, I obtain the correct ranking. It gives the same rank for equal values.
Example from the following data: rank(abs(0.2,0.2,-0.2))= 4 4 4
k=c(-.9,.2,-1.1,.5,-.8,.3,-1,.6,-1.3,-.2,-1.5,.1,-1.2,-.1,-1.4,.2,-.6,.5,-.8,.8)
rank(abs(k))
[1] 14.0 4.0 16.0 7.5 12.0 6.0 15.0 9.5 18.0 4.0 20.0 1.5 17.0 1.5 19.0
[16] 4.0 9.5 7.5 12.0 12.0
2- When I obtain the same data vector from some operations, I obtain a wrong ranking. It gives the different ranks for equal values.
Example from the following data: rank(abs(0.2,-0.2,0.2))= 3 4.5 4.5
x=c(2.9,3,2.5,2.6,3.2)
y=c(3.8,2.7,4,2.4)
z=rep(0,length(x)*length(y))
sizez=1
for(i in 1:length(x))
+ for(j in 1:length(y))
+ {z[sizez]=x[i]-y[j]; sizez=sizez+1;}
z
[1] -0.9 0.2 -1.1 0.5 -0.8 0.3 -1.0 0.6 -1.3 -0.2 -1.5 0.1 -1.2 -0.1 -1.4
[16] 0.2 -0.6 0.5 -0.8 0.8
R=rank(abs(z))
R
[1] 14.0 3.0 16.0 7.5 11.5 6.0 15.0 10.0 18.0 4.5 20.0 1.5 17.0 1.5 19.0
[16] 4.5 9.0 7.5 11.5 13.0
I try many times but I have not known what is the mistake.
Can you kindly help me to solve this problem?
Thank you.
Ibtesam.
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