\m2v operator?
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svrieze
Joined: 01/03/2010
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Hello,
What would be the R or OpenMx equivalent of the \m2v operator in Classic Mx?
Related question: if I define in R my own function that performs this operation, can I use that function within the mxAlgebra command?
-Scott
Apologies, I believe I've
Apologies, I believe I've found my own answer.
For \m2v(X) one can use as.vector(t(X)).
-Scott
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In reply to Apologies, I believe I've by svrieze
If I remember correctly,
If I remember correctly, as.vector is not supported by OpenMx. Use the functions cvectorize or rvectorize to perform either row or column vectorization. There is a wiki page with matrix operators and functions but it is missing these two (sorry!). To write your own matrix function, you need to provide an implementation in C for OpenMx. There is a HOWTO on the wiki. You can also define an arbitrary objective function in R. See the user guide for help on that.
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In reply to If I remember correctly, by mspiegel
The wiki page is up to date
The wiki page is up to date again: http://openmx.psyc.virginia.edu/wiki/matrix-operators-and-functions
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Hello again, Related
Hello again,
Related question: how can I use colMeans() in an mxAlgebra command?
In some releases it appears that colMeans was a legitimate function within mxAlgebra (http://openmx.psyc.virginia.edu/docs/OpenMx/0.2.1-922/_static/Rdoc/mxAlgebra.html).
In the latest manual it is not listed as a viable function under the mxAlgebra command (http://openmx.psyc.virginia.edu/docs/OpenMx/latest/_static/Rdoc/mxAlgebra.html).
Thanks for the quick and helpful replies,
-Scott
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In reply to Hello again, Related by svrieze
Yes. colMeans used to be
Yes. colMeans used to be listed in the documentation, but that was an error as it wasn't implemented. We'll put it on the TODO list, it shouldn't be too hard to implement rowMeans() and colMeans(). At best, you can currently compute the column means explicitly, although it is a pain. For example, if A is a 3 x 3 MxMatrix or MxAlgebra, then the column mean is:
col1 <- mxAlgebra(sum(A[,1]) / 3, name = "col1")
col2 <- mxAlgebra(sum(A[,2]) / 3, name = "col2")
col3 <- mxAlgebra(sum(A[,3]) / 3, name = "col3")
colMean <- mxAlgebra(rbind(col1, col2, col3), name = "colMean")
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In reply to Yes. colMeans used to be by mspiegel
Or with a bit more generality
Or with a bit more generality using the number of rows in A and a bit of matrix algebra
v <- mxMatrix("Full", 1, dim(A@values)[1], values=1/dim(A@values)[1], name="v")
colMean <- mxAlgebra(v %*% A, name="colMeansOfA")
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In reply to Or with a bit more generality by neale
And similarly for row means v
And similarly for row means
v <- mxMatrix("Full", 1, dim(A@values)[2], values=1/dim(A@values)[2], name="v")
rowlMean <- mxAlgebra(A %*% v, name="rowMeansOfA")
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In reply to And similarly for row means v by Steve
I don't have access to R at
I don't have access to R at the moment, but I believe that dims(a) will work, where a is a MxMatrix object. Or if that doesn't work try nrow(a) and ncol(a).
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In reply to Hello again, Related by svrieze
Opened a ticket for colMeans
Opened a ticket for colMeans and rowMeans: http://openmx.psyc.virginia.edu/issue/2010/06/mxalgebra-wishlist
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In reply to Opened a ticket for colMeans by mspiegel
Agreed these functions
Agreed these functions (
ceiling, floor, trunk, round
dim
rowMeans, colMeans
cov2cor)
Would be useful. There are some gotchas with cov2cor - it fails when diagonal elements are non-positive. I guess it will end up with NaNs in the rows and cols of any non-pos elements. In classic Mx it would throw an error which was inconvenient. NaN is much better.
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In reply to Agreed these functions by neale
Extra vote for a speedy
Extra vote for a speedy cov2cor() postRelease(1.0) , esp with error catching to return NA :-)
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