stackoverflow:converting-matrix-to-dataframe-works-in-one-ca

> ## Solution: reshape is obsolete.  Use reshape2 with acast:
> library(reshape2)
>
> t = 0:3
> thesd = 0.1
> dat = data.frame(
+     a1 = sin(2*pi*t/length(t)) + rnorm(t, sd=thesd),
+     b1 = sin(2*pi*t/length(t) - pi) + rnorm(t, sd=thesd),
+     c1 = sin(2*pi*t/length(t) - pi/2) + rnorm(t, sd=thesd),
+     t  = t
+ )
>
> test_mx = acast(melt(dat, id.vars="t"), variable ~ t)
> as.data.frame(test_mx)
             0           1            2           3
a1  0.00881139  1.00898951  0.007116073 -0.82006264
b1 -0.12102260 -0.97846639 -0.095028245  0.84406265
c1 -0.89275912 -0.02657619  1.214589078  0.07990604