How to extract a vector from a list of vectors via matrix in R
Problem:
I have a number of vectors. I would like to sign numbers to these vectors starting from 1 to n. Then, I would like to convert these number to a lower.triangular matrix. After that, I would like to extract the vectors comes at the last row of the matrix.
Steps of the problem:
Sign numbers
nvectors from1ton.Convert these numbers to a
lower.triangularmatrix M.Then, extract the vectors that match the numbers at the last row of the matrix M.
Example:
Assume that I have a list of 10 vectors (X):
X <- list(x1=c(1:3), x2=(2:5), x3=c(4:2), x4=c(5:7), x5=c(12,34,54), x6=c(3:6), x7=c(3:6), x8=c(3,4,5), x9=c(44,56,7), x10=c(34,5,4))
Then, I would like to order them from 1 to 10, where 1 refers to the first vector, and so on. Then, I will have a vector of these numbers, say x = c(1:10). Then, I would like to convert it to a lower triangular matrix M.
M <- matrix(0,5,5)
> M[lower.tri(M, diag=FALSE)] <- x
> M
[,1] [,2] [,3] [,4] [,5]
[1,] 0 0 0 0 0
[2,] 1 0 0 0 0
[3,] 2 5 0 0 0
[4,] 3 6 8 0 0
[5,] 4 7 9 10 0
Now, I would like to extract, the last row.
> tail(M, 1)
[,1] [,2] [,3] [,4] [,5]
[5,] 4 7 9 10 0
> newX <- as.vector(tail(M,1))
> newX
[1] 4 7 9 10 0
Now the wanted vectors (to be extracted from the whole vectors) are 4, 7, 9, and 10. In other words, I need to extract, x4, x7, x9, and x10.
Hence, I would like to extract the vectors match these number.
Any idea or help, please?
r
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
add a comment |
Problem:
I have a number of vectors. I would like to sign numbers to these vectors starting from 1 to n. Then, I would like to convert these number to a lower.triangular matrix. After that, I would like to extract the vectors comes at the last row of the matrix.
Steps of the problem:
Sign numbers
nvectors from1ton.Convert these numbers to a
lower.triangularmatrix M.Then, extract the vectors that match the numbers at the last row of the matrix M.
Example:
Assume that I have a list of 10 vectors (X):
X <- list(x1=c(1:3), x2=(2:5), x3=c(4:2), x4=c(5:7), x5=c(12,34,54), x6=c(3:6), x7=c(3:6), x8=c(3,4,5), x9=c(44,56,7), x10=c(34,5,4))
Then, I would like to order them from 1 to 10, where 1 refers to the first vector, and so on. Then, I will have a vector of these numbers, say x = c(1:10). Then, I would like to convert it to a lower triangular matrix M.
M <- matrix(0,5,5)
> M[lower.tri(M, diag=FALSE)] <- x
> M
[,1] [,2] [,3] [,4] [,5]
[1,] 0 0 0 0 0
[2,] 1 0 0 0 0
[3,] 2 5 0 0 0
[4,] 3 6 8 0 0
[5,] 4 7 9 10 0
Now, I would like to extract, the last row.
> tail(M, 1)
[,1] [,2] [,3] [,4] [,5]
[5,] 4 7 9 10 0
> newX <- as.vector(tail(M,1))
> newX
[1] 4 7 9 10 0
Now the wanted vectors (to be extracted from the whole vectors) are 4, 7, 9, and 10. In other words, I need to extract, x4, x7, x9, and x10.
Hence, I would like to extract the vectors match these number.
Any idea or help, please?
r
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
add a comment |
Problem:
I have a number of vectors. I would like to sign numbers to these vectors starting from 1 to n. Then, I would like to convert these number to a lower.triangular matrix. After that, I would like to extract the vectors comes at the last row of the matrix.
Steps of the problem:
Sign numbers
nvectors from1ton.Convert these numbers to a
lower.triangularmatrix M.Then, extract the vectors that match the numbers at the last row of the matrix M.
Example:
Assume that I have a list of 10 vectors (X):
X <- list(x1=c(1:3), x2=(2:5), x3=c(4:2), x4=c(5:7), x5=c(12,34,54), x6=c(3:6), x7=c(3:6), x8=c(3,4,5), x9=c(44,56,7), x10=c(34,5,4))
Then, I would like to order them from 1 to 10, where 1 refers to the first vector, and so on. Then, I will have a vector of these numbers, say x = c(1:10). Then, I would like to convert it to a lower triangular matrix M.
M <- matrix(0,5,5)
> M[lower.tri(M, diag=FALSE)] <- x
> M
[,1] [,2] [,3] [,4] [,5]
[1,] 0 0 0 0 0
[2,] 1 0 0 0 0
[3,] 2 5 0 0 0
[4,] 3 6 8 0 0
[5,] 4 7 9 10 0
Now, I would like to extract, the last row.
> tail(M, 1)
[,1] [,2] [,3] [,4] [,5]
[5,] 4 7 9 10 0
> newX <- as.vector(tail(M,1))
> newX
[1] 4 7 9 10 0
Now the wanted vectors (to be extracted from the whole vectors) are 4, 7, 9, and 10. In other words, I need to extract, x4, x7, x9, and x10.
Hence, I would like to extract the vectors match these number.
Any idea or help, please?
r
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
Problem:
I have a number of vectors. I would like to sign numbers to these vectors starting from 1 to n. Then, I would like to convert these number to a lower.triangular matrix. After that, I would like to extract the vectors comes at the last row of the matrix.
Steps of the problem:
Sign numbers
nvectors from1ton.Convert these numbers to a
lower.triangularmatrix M.Then, extract the vectors that match the numbers at the last row of the matrix M.
Example:
Assume that I have a list of 10 vectors (X):
X <- list(x1=c(1:3), x2=(2:5), x3=c(4:2), x4=c(5:7), x5=c(12,34,54), x6=c(3:6), x7=c(3:6), x8=c(3,4,5), x9=c(44,56,7), x10=c(34,5,4))
Then, I would like to order them from 1 to 10, where 1 refers to the first vector, and so on. Then, I will have a vector of these numbers, say x = c(1:10). Then, I would like to convert it to a lower triangular matrix M.
M <- matrix(0,5,5)
> M[lower.tri(M, diag=FALSE)] <- x
> M
[,1] [,2] [,3] [,4] [,5]
[1,] 0 0 0 0 0
[2,] 1 0 0 0 0
[3,] 2 5 0 0 0
[4,] 3 6 8 0 0
[5,] 4 7 9 10 0
Now, I would like to extract, the last row.
> tail(M, 1)
[,1] [,2] [,3] [,4] [,5]
[5,] 4 7 9 10 0
> newX <- as.vector(tail(M,1))
> newX
[1] 4 7 9 10 0
Now the wanted vectors (to be extracted from the whole vectors) are 4, 7, 9, and 10. In other words, I need to extract, x4, x7, x9, and x10.
Hence, I would like to extract the vectors match these number.
Any idea or help, please?
r
r
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
asked Nov 15 '18 at 6:37
MaryamMaryam
28911
28911
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
You could use paste:
X[paste0("x", newX[newX != 0])]
$`x4`
[1] 5 6 7
$x7
[1] 3 4 5 6
$x9
[1] 44 56 7
$x10
[1] 34 5 4
paste0("x", newX[newX != 0] will create the character vector "x4", "x7", "x9", "x10" which you can use for indexing the list.
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
add a comment |
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1 Answer
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1 Answer
1
active
oldest
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active
oldest
votes
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votes
You could use paste:
X[paste0("x", newX[newX != 0])]
$`x4`
[1] 5 6 7
$x7
[1] 3 4 5 6
$x9
[1] 44 56 7
$x10
[1] 34 5 4
paste0("x", newX[newX != 0] will create the character vector "x4", "x7", "x9", "x10" which you can use for indexing the list.
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
add a comment |
You could use paste:
X[paste0("x", newX[newX != 0])]
$`x4`
[1] 5 6 7
$x7
[1] 3 4 5 6
$x9
[1] 44 56 7
$x10
[1] 34 5 4
paste0("x", newX[newX != 0] will create the character vector "x4", "x7", "x9", "x10" which you can use for indexing the list.
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
add a comment |
You could use paste:
X[paste0("x", newX[newX != 0])]
$`x4`
[1] 5 6 7
$x7
[1] 3 4 5 6
$x9
[1] 44 56 7
$x10
[1] 34 5 4
paste0("x", newX[newX != 0] will create the character vector "x4", "x7", "x9", "x10" which you can use for indexing the list.
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
You could use paste:
X[paste0("x", newX[newX != 0])]
$`x4`
[1] 5 6 7
$x7
[1] 3 4 5 6
$x9
[1] 44 56 7
$x10
[1] 34 5 4
paste0("x", newX[newX != 0] will create the character vector "x4", "x7", "x9", "x10" which you can use for indexing the list.
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
edited Nov 15 '18 at 7:02
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
answered Nov 15 '18 at 6:56
LAPLAP
5,7202622
5,7202622
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
add a comment |
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
1
1
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
Thank you so much for your very clever help. I thought I will need some lines of codes to done this.
– Maryam
Nov 15 '18 at 7:58
1
1
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
You are welcome! Often enough R surprises you with a really simple solution for a seemingly big problem :)
– LAP
Nov 15 '18 at 7:59
add a comment |
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