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How to remove a column from matrix in R by using its name?
To remove a column from matrix in R by using its name, we can follow the below steps −
First of all, create a matrix
Then, add names to columns of the matrix.
After that, subset the matrix by deselecting the desired column with negation and single square brackets for subsetting.
Example
Create the matrix
Let’s create a matrix as shown below −
M<-matrix(rnorm(75),ncol=3) M
Output
On executing, the above script generates the below output(this output will vary on your system due to randomization) −
[,1] [,2] [,3] [1,] 0.34927825 0.36395550 -1.4312211 [2,] 0.78629719 -0.45147440 -0.1596172 [3,] 0.88492110 -0.16546013 -1.7026552 [4,] -2.28671282 -1.84818688 1.3984903 [5,] 0.02194021 -0.54682956 -2.5447857 [6,] 1.51718583 -0.34319221 -1.7286530 [7,] -0.04924026 -0.88751938 -0.1783474 [8,] -0.07423773 -0.27037703 0.3952588 [9,] 1.14769892 -1.71712705 0.1677618 [10,] 0.71949312 -0.73954427 0.4089844 [11,] -0.33954351 -0.01039998 0.6405262 [12,] 0.11824754 2.27291701 0.2234398 [13,] 0.37339259 -0.50529084 1.0764492 [14,] 0.05557717 -0.61960682 0.4721451 [15,] 1.87575124 1.66763649 0.8596300 [16,] -0.57575272 -0.44936940 0.6154190 [17,] 0.85030730 -1.21989570 1.5136665 [18,] 1.19599580 0.33216810 -0.3205572 [19,] 0.64010472 -0.26696943 1.3040537 [20,] 0.74811799 0.65594635 -1.2104943 [21,] -0.27932027 -1.41589620 -0.1530550 [22,] -0.37549109 -1.08739383 0.7536317 [23,] 0.07836645 1.14317049 -1.1269287 [24,] 0.44175649 0.21147460 -1.3777469 [25,] 1.11577514 0.28621068 0.0819287
Add the column names
Using colnames function to add the column names to matrix M −
M<-matrix(rnorm(75),ncol=3)
colnames(M)<-c("First","Second","Third")
MOutput
First Second Third [1,] -0.63798951 -0.08312581 -0.29548313 [2,] 0.81035121 0.32946453 0.26934501 [3,] 1.17310898 -0.16824116 1.44146054 [4,] -1.46085561 -1.01480047 0.48119221 [5,] -0.60117020 -0.71335771 0.56736308 [6,] 1.39032577 0.45488133 1.12518802 [7,] 1.24992297 -0.79274785 0.88435795 [8,] -0.46766814 -0.61113426 0.87081178 [9,] -0.50900441 0.32142161 0.06270336 [10,] 0.53407605 0.75097220 0.62138186 [11,] -0.31153258 -0.19474785 1.31048238 [12,] -0.90701432 0.25399274 -0.51568591 [13,] 0.48485802 -0.19454370 -0.84981770 [14,] 0.22094696 -1.04421982 -1.08446966 [15,] 0.28317116 -0.07426917 0.41447679 [16,] 0.60986979 2.20385278 1.02703888 [17,] -1.03122232 -0.26323809 -0.22929783 [18,] -1.39070018 3.28175028 0.31980456 [19,] 0.20176785 1.64951864 -0.51179577 [20,] -0.46897146 1.16688302 -1.76417685 [21,] 0.43936821 -0.70327534 0.05285094 [22,] -0.69668353 0.65657864 0.04483215 [23,] 0.05226474 0.14180989 1.31808786 [24,] 0.16654568 0.74867083 1.16400816 [25,] -1.16417323 -0.42192382 0.87543185
Remove the column from matrix using column name
Subset the matrix by deselecting the Second column with negation and single square brackets as shown below −
M<-matrix(rnorm(75),ncol=3)
colnames(M)<-c("First","Second","Third")
M<M[,colnames(M)!="Second"]
MOutput
First Third [1,] 0.34927825 -1.4312211 [2,] 0.78629719 -0.1596172 [3,] 0.88492110 -1.7026552 [4,] -2.28671282 1.3984903 [5,] 0.02194021 -2.5447857 [6,] 1.51718583 -1.7286530 [7,] -0.04924026 -0.1783474 [8,] -0.07423773 0.3952588 [9,] 1.14769892 0.1677618 [10,] 0.71949312 0.4089844 [11,] -0.33954351 0.6405262 [12,] 0.11824754 0.2234398 [13,] 0.37339259 1.0764492 [14,] 0.05557717 0.4721451 [15,] 1.87575124 0.8596300 [16,] -0.57575272 0.6154190 [17,] 0.85030730 1.5136665 [18,] 1.19599580 -0.3205572 [19,] 0.64010472 1.3040537 [20,] 0.74811799 -1.2104943 [21,] -0.27932027 -0.1530550 [22,] -0.37549109 0.7536317 [23,] 0.07836645 -1.1269287 [24,] 0.44175649 -1.3777469 [25,] 1.11577514 0.0819287
Updated on: 16-Nov-2021
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