R | Variable Conversion

The “as….” explicitly converts the data to whatever you desired outcome.

  • as.array(x)
  • as.data.frame(x)
  • as.numeric(x)
  • as.logical(x)
  • as.vector(x)
  • as.matrix(x)
  • as.complex(x)
  • as.character(x)
  • … convert type; for a complete list, use methods(as)
to one long
vector
to
matrix
to
data frame
from
vector
c(x,y) cbind(x,y)
rbind(x,y)
data.frame(x,y)
from
matrix
as.vector(mymatrix) as.data.frame(mymatrix)
from
data frame
as.matrix(myframe)

If you are interested in testing data types use “is…” instead of “as…” this will allow R to return a TRUE or FALSE outcomes.

R | Data Creation

Ever wonder how to generate data within R?

  • c(…) generic function to combine arguments with the default forming a vector; with recursive=TRUE descends through lists combining all elements into one vector
  • from:to generates a sequence; “:” has operator priority; 1:4 + 1 is “2,3,4,5”
  • seq(from,to) generates a sequence by= specifies increment; length=specifies desired length
  • seq(along=x) generates 1, 2, …, length(along); useful for for loops
  • rep(x,times) replicate x times; use each= to repeat “each” element of x each times; rep(c(1,2,3),2) is 1 2 3 1 2 3;
  • rep(c(1,2,3),each=2) is 1 1 2 2 3 3
  • data.frame(…) create a data frame of the named or unnamed arguments; data.frame(v=1:4,ch=c(“a”,”B”,”c”,”d”),n=10);
  • shorter vectors are recycled to the length of the longest
  • list(…) create a list of the named or unnamed arguments; list(a=c(1,2),b=”hi”,c=3i);
  • array(x,dim=) array with data x; specify dimensions like dim=c(3,4,2); elements of x recycle if x is not long enough
  • matrix(x,nrow=,ncol=) matrix; elements of x recycle
  • factor(x,levels=) encodes a vector x as a factor
  • gl(n,k,length=n*k,labels=1:n) generate levels (factors) by specifying the pattern of their levels; k is the number of levels, and n is the number of replications expand.grid() a data frame from all combinations of the supplied vectors or factors
  • rbind(…) combine arguments by rows for matrices, data frames, and others
  • cbind(…) id. by columns