HOw to achieve big vector times big dataframe in R?

apply((t(as.matrix(b)) * a), 2, sum)

should do what you want.

Why this works; see,
http://cran.r-project.org/doc/manuals/r-release/R-intro.html#The-recycling-rule
and the paragraph before that.

Jan



Tammy Ma <metal_licaling at live.com> schreef:

HI,

I have the following question:

Vector a with lenght 150

A B C D.........

dataframe b with dim 908X150

1   1   1   1.....
2   2   2   2
3   3   3   3
4   4   4   4
................

final result I want is the vector with length 908:
A*1+B*1+C*1+D*1+.....
A*2+B*2+C*2+D*2+.....
A*3+B*3+C*3+D*3+.....
A*4+B*4+C*4+D*4+.....
....

because of too large dimension, how can I achieve this in R? Thanks.

Kind Regards,
Tammy


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