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how to apply a function to every row of a matrix (or a data frame) in RR - how to call apply-like function on each row of dataframe with multiple arguments from each row of the df
I want to apply a function to each row in a data frame, however, R applies it to each column by default. How do I force it otherwise?
> a = as.data.frame(list(c(1,2,3),c(10,0,6)),header=T) > a c.1..2..3. c.10..0..6. 1 1 10 2 2 0 3 3 6 > sapply(a,min) c.1..2..3. c.10..0..6. 1 0 I wanted something like
1 2 2 0 3 3 
527
You can use the apply() function to apply a function to each row in a matrix or data frame in R.
In R, the easiest way to repeat rows is with the REP() function. This function selects one or more observations from a data frame and creates one or more copies of them.
Apply any function to all R data frame You can set the MARGIN argument to c(1, 2) or, equivalently, to 1:2 to apply the function to each value of the data frame. If you set MARGIN = c(2, 1) instead of c(1, 2) the output will be the same matrix but transposed. The output is of class “matrix” instead of “data.
One of the most famous and most used features of R is the *apply() family of functions, such as apply() , tapply() , and lapply() . Here, we'll look at apply() , which instructs R to call a user-specified function on each of the rows or each of the columns of a matrix.
You want apply (see the docs for it). apply(var,1,fun) will apply to rows, apply(var,2,fun) will apply to columns.
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