Still a bit new to R and would appreciate some guidance. I have produced a relatedness matrix but before I melt it to create my edge list, I want to set all the values in each row to 0 EXCEPT for the row maximum. Any tips on how to do this?
I have no idea what to try.
CodePudding user response：
You can use apply replace:
m <- matrix(1:9, 3)
[,1] [,2] [,3]
[1,] 1 4 7
[2,] 2 5 8
[3,] 3 6 9
t(apply(m, 1, function(x) replace(x, x != max(x), 0)))
[,1] [,2] [,3]
[1,] 0 0 7
[2,] 0 0 8
[3,] 0 0 9
or with tapply:
do.call(rbind, tapply(m, row(m), function(x) replace(x, x != max(x), 0)))
CodePudding user response：
max.col will be useful here:
m <- matrix(sample(100), 10, 10)
m
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#> [1,] 93 78 98 14 11 74 63 5 38 43
#> [2,] 34 1 55 64 67 15 97 37 4 89
#> [3,] 52 25 75 20 77 28 65 84 39 49
#> [4,] 3 45 79 50 18 60 48 16 13 42
#> [5,] 24 69 91 44 9 87 17 62 2 32
#> [6,] 95 94 68 53 99 70 82 36 66 40
#> [7,] 92 41 23 54 30 21 88 81 72 83
#> [8,] 59 100 56 27 10 46 6 12 26 19
#> [9,] 90 35 71 51 8 86 76 29 31 96
#> [10,] 58 33 47 73 85 61 80 57 7 22
m[-(1:nrow(m) (max.col(m) - 1L)*ncol(m))] <- 0
m
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#> [1,] 0 0 98 0 0 0 0 0 0 0
#> [2,] 0 0 0 0 0 0 97 0 0 0
#> [3,] 0 0 0 0 0 0 0 84 0 0
#> [4,] 0 0 79 0 0 0 0 0 0 0
#> [5,] 0 0 91 0 0 0 0 0 0 0
#> [6,] 0 0 0 0 99 0 0 0 0 0
#> [7,] 92 0 0 0 0 0 0 0 0 0
#> [8,] 0 100 0 0 0 0 0 0 0 0
#> [9,] 0 0 0 0 0 0 0 0 0 96
#> [10,] 0 0 0 0 85 0 0 0 0 0
With a numeric matrix with named rows/columns:
m <- matrix(runif(100), 10, 10, dimnames = list(LETTERS[1:10], LETTERS[11:20]))
m
#> K L M N O P Q R S T
#> A 0.8455340 0.97713257 0.89784675 0.9116978 0.5132513 0.4197610 0.39154932 0.5499533 0.74761367 0.04024061
#> B 0.2574573 0.42892093 0.55113837 0.1347042 0.9728912 0.2104251 0.51084878 0.6308227 0.08114070 0.08541959
#> C 0.3393108 0.14198061 0.12190379 0.2433768 0.1043313 0.2526678 0.21550723 0.5086210 0.07906360 0.88046001
#> D 0.1492551 0.66689551 0.04958598 0.3519842 0.2420030 0.5919464 0.27392652 0.2029944 0.32210388 0.90704707
#> E 0.4473961 0.61912114 0.58880869 0.9073496 0.7760235 0.7955465 0.43140215 0.5572331 0.32165581 0.90433083
#> F 0.0279498 0.86375368 0.35372818 0.5033064 0.4016708 0.6530612 0.18887117 0.3123320 0.03582699 0.27059191
#> G 0.1848169 0.11436509 0.84722483 0.8874162 0.2558677 0.6839403 0.85603179 0.5178988 0.53953932 0.55142390
#> H 0.1056349 0.48193774 0.44023254 0.5574092 0.9154315 0.6261866 0.51314697 0.5838974 0.92684901 0.75310930
#> I 0.9220023 0.86660126 0.87581045 0.2354375 0.9385472 0.3527555 0.09545731 0.1028695 0.99012272 0.71308235
#> J 0.9915948 0.04529849 0.40984050 0.4431233 0.8482269 0.1817989 0.73221712 0.6340093 0.68836208 0.69083152
m[-(1:nrow(m) (max.col(m) - 1L)*ncol(m))] <- 0
m
#> K L M N O P Q R S T
#> A 0.0000000 0.9771326 0 0.0000000 0.0000000 0 0 0 0.0000000 0.0000000
#> B 0.0000000 0.0000000 0 0.0000000 0.9728912 0 0 0 0.0000000 0.0000000
#> C 0.0000000 0.0000000 0 0.0000000 0.0000000 0 0 0 0.0000000 0.8804600
#> D 0.0000000 0.0000000 0 0.0000000 0.0000000 0 0 0 0.0000000 0.9070471
#> E 0.0000000 0.0000000 0 0.9073496 0.0000000 0 0 0 0.0000000 0.0000000
#> F 0.0000000 0.8637537 0 0.0000000 0.0000000 0 0 0 0.0000000 0.0000000
#> G 0.0000000 0.0000000 0 0.8874162 0.0000000 0 0 0 0.0000000 0.0000000
#> H 0.0000000 0.0000000 0 0.0000000 0.0000000 0 0 0 0.9268490 0.0000000
#> I 0.0000000 0.0000000 0 0.0000000 0.0000000 0 0 0 0.9901227 0.0000000
#> J 0.9915948 0.0000000 0 0.0000000 0.0000000 0 0 0 0.0000000 0.0000000