Apply a function to every row of a matrix or a data frame

by

You simply use the apply() function:

R> M <- matrix(1:6, nrow=3, byrow=TRUE)
R> M
     [,1] [,2]
[1,]    1    2
[2,]    3    4
[3,]    5    6
R> apply(M, 1, function(x) 2*x[1]+x[2])
[1]  4 10 16
R>

This takes a matrix and applies a (silly) function to each row. You pass extra arguments to the function as fourth, fifth, … arguments to apply().

More Related Contents:

  1. how to apply a function on a data set?
  2. Concatenate row-wise across specific columns of dataframe
  3. Last Observation Carried Forward In a data frame? [duplicate]
  4. Apply function to each column in a data frame observing each columns existing data type
  5. Loop through a R matrix row-wise and print elements [duplicate]
  6. Reshape three column data frame to matrix (“long” to “wide” format) [duplicate]
  7. Split a large dataframe into a list of data frames based on common value in column
  8. data.table objects assigned with := from within function not printed
  9. Returning multiple objects in an R function [duplicate]
  10. Multiply rows of matrix by vector?
  11. All Levels of a Factor in a Model Matrix in R
  12. R Apply() function on specific dataframe columns
  13. How can I create a correlation matrix in R?
  14. Why apply() returns a transposed xts matrix?
  15. Rotate a Matrix in R by 90 degrees clockwise
  16. How to paste a string on each element of a vector of strings using apply in R?
  17. R – How to get row & column subscripts of matched elements from a distance matrix
  18. How do I override a non-visible function in the package namespace?
  19. Why does as.factor return a character when used inside apply?
  20. What is the meaning of the dollar sign “$” in R function()?
  21. rbind data frames based on a common pattern in data frame name
  22. How `poly()` generates orthogonal polynomials? How to understand the “coefs” returned?
  23. R: Plotting a 3D surface from x, y, z
  24. Directly creating dummy variable set in a sparse matrix in R
  25. R: x ‘probs’ outside [0,1]
  26. Create frequency tables for multiple factor columns in R
  27. R function not returning values
  28. R specify function environment
  29. How to calculate adjacency matrices in R
  30. What does the error “arguments imply differing number of rows: x, y” mean?

Leave a Comment