change cell values
On Jul 3, 2013, at 2:27 PM, JiangZhengyu wrote:
Dear R experts, I have two matrices (mat1 & mat2) with the same dimension & the cells (row and column) are corresponding to each other. I want to change cell values to NA given values of the corresponding cells in mat1 and mat2 are both <1. E.g. both mat1[2,3] and mat2[2,3] are <1, I will put mat1[2,3]=NA, and mat2[2,3]=NA; if either mat1[2,3]>=1 or mat2[2,3]>=1, I will save both cells. I tried the code, but not working. Could anyone can help fix the problem? mat1[mat1<1&mat2<1]=NA mat2[mat1<1&mat2<1]=NA
I beleive the problem is that after the first NA assignment that mat1 will have changed. You need to record the status of both mat1 and mat2 before the change:
both <- mat1<1&mat2<1 both
[,1] [,2] [,3] [,4] [1,] FALSE FALSE TRUE TRUE [2,] TRUE FALSE TRUE TRUE [3,] FALSE TRUE FALSE TRUE
mat1[both] <- NA mat2[both] <- NA mat1
[,1] [,2] [,3] [,4] [1,] 1.5599872 2.209537 NA NA [2,] NA -1.144140 NA NA [3,] -0.8516326 NA 1.000368 NA
mat2
[,1] [,2] [,3] [,4] [1,] 0.8863107 -0.3863741 NA NA [2,] NA 1.3185811 NA NA [3,] 1.4487338 NA 1.051689 NA There is also formalism: is.na(object) <- logical.vector so it could have been: is.na(mat1) <- both is.na(mat2) <- both
mat1=matrix(rnorm(12),3) mat2=matrix(rnorm(12),3) mat1
[,1] [,2] [,3] [,4] [1,] -1.3387075 -0.7142333 -0.5614211 0.1846955 [2,] -0.7936087 -0.2215797 -0.3686067 0.7328731 [3,] 0.6505082 0.1826019 1.5577883 -1.5580384
mat2
[,1] [,2] [,3] [,4] [1,] 0.4331573 -1.8086826 -1.7688123 -1.4278934 [2,] -0.1841451 0.1738648 -1.1086942 1.3065109 [3,] -1.0827245 -0.4143808 -0.6889405 0.4046203 [[alternative HTML version deleted]]
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
David Winsemius Alameda, CA, USA