I am using SPSS and have about 300 variables (categorical, scalar and ordinal) to model. I need an Easy / Quick way to create interaction variable composites for Logistic Regression where interactions exist. R does this automatically and creates about 158 composites (variables that have interactions) – there does not appear to be any automated way to create and input interaction variables in SPSS; having to manually input and or test these 158 composites every time I run a new model is going to be A LOT OF WORK!! Any suggestions on a quick way to do this?
If you are going to be repeatedly running this model and need a way to create these synthetic variables, you should most likely create a syntax file that will do it for you. When you use the GUI in SPSS to run a command, SPSS generates the syntax in the output window. You can copy this syntax and use it to create your own script. So, for instance you might write something like this:
DO IF (!MISSING Var1).
COMPUTE Var2 = Var1 * dummy1.
END IF.
EXECUTE.
And sadly, yes you would have to write this block of code 300 times the first go around, but in the future you can simply run it and have all the new variable computed.
Another approach is to name your variables sequentially and use a loop to process them. So assuming that your variables were sequentially named VarA, VarB, & VarC, then you could do a loop like so:
VECTOR VectorVar = VarA TO VarC.
LOOP #cnt = 1 to 3 by 1.
COMPUTE VectorVar(#cnt) = VectorVar * dummy1.
ENDLOOP.
EXECUTE.
Are you really looking to put in all 158 interaction terms? I'd be skeptical of that approach. But if you want to build variables representing all these interaction terms rather than specify them in the model, you can do it with the CREATE DUMMIES extension command available from the SPSS Community website (www.ibm.com/developerworks/spssdevcentral).
You could also use Python programmability to build the explicit interaction terms in the logistic procedure.
HTH,
Jon Peck
Related
I'm trying to use the python interface of SCIP tool (https://github.com/scipopt/PySCIPOpt) to solve a mixed-integer optimization problem.
I want to define an OR-constraint with three constraints, but only one of them must be satisfied.
For example, I want to minimize a variable x with three constraints x>=1, x>=2, x>=3, but only one of them must be valid, and then minimize the value of x. Of course the result should be x=1.
However the OR-constraint API addConsOr requires both the constraint list and result variable (resvar, resultant variable of the operation). While I can provide the list of constraints, I don't know the meaning of result variable in the second function parameter. When I set the second parameter to a new variable, the following code cannot run and result in segmentation fault.
from pyscipopt import Model
model = Model()
x = model.addVar(vtype = "I")
b = model.addVar(vtype="B")
model.addConsOr([x>=1, x>=2, x>=3], b)
model.setObjective(x, "minimize")
model.optimize()
print("Optimal value:", model.getObjVal())
Also, setting the second variable to True also gets segmentation fault.
model.addConsOr([x>=1, x>=2, x>=3], True)
What you are describing is not an OR-constraint. An or-constraint is a constraint that takes into account a set of binary variables and gets the result as an OR of these values, as explained in the SCIP documentation.
What you want is a general disjunctive constraint. Those exist in SCIP as SCIPcreateConsDisjunction but are not wrapped in the Python API yet. Fortunately, you can extend the API yourself quite easily. Simply add the correct function to scip.pxd and define the wrapper in scip.pyx. Just look at how it is done for the existing constraint types and do it the same way. The people over at the PySCIPopt GitHub will be happy if you create a pull-request with your changes.
I need some help in creating a VI that generates virtual or calculated channels based on several channels I measure.
e.g.
I measure voltage on several AI, lets say, ch A,B,C,D,E were B,C and E represent current on a shunt and would like to calculate a the power of the system
Q[A] = B+C
R[W] = A*Q
S[W] = D*E
T[W] = R+S
I would like to load the equations externally from a configuration file that may vary from one project to another equations would come in a format of a string Q=A+B , R= A*Q .....
*(during a run equation and channel count don't change - only when loading config).
The main issues that I am facing is that the inputs to each equation may have dependencies on virtual channels that do not have data yet
Was trying to use:
formula nodes/ Math scripts: https://zone.ni.com/reference/en-XX/help/371361R-01/lvconcepts/formula_nodes/
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x30HCAQ&l=en-IL
All data that should be chunked into a data stream (continues sampling) that can be presented on a Chart/Graph and saved to CSV/TDMS
do I need some additional packages?
I have tried the following based on the the example given - getting strange result
Answer
The elements you are looking for are not the Formula/Math Nodes but rather the:
Formula Parsing VIs
Using these VIs you are able to pass a calculation in the form of a string and an array of variable names and then evaluate the formula. This allows for run-time variable scripting, where most other nodes require compile time formula evaluation (With the exception of the python node).
Example
Example of using a very simple program to evaluate two different calculations using the same values and variables.
I want to store a list of variable names in a new local variable, such that I do not have to type a long list of variable names for each regression. I am using Stata 14.
E.g., I have the following 5 independent variables: a b c d e and one dependent variable: f
I don't want:
regress f a b c d e
But I want something like:
regress f allvar
How can I generate allvar?
Unfortunately, this does not work
local allvar a b c d e
The following works fine.
clear
set more off
sysuse auto
// first regressions
regress price mpg rep78 weight
// second regression
local allvars mpg rep78 weight
regress price `allvars'
Unless you show us something reproducible and/or more explicit, it's difficult to see what the problem is. A report only mentioning "does not work" is usually useless.
See also the keyword _all in help varlist.
You are using a local macro. If you are running the code by parts, then don't. You need to run the whole code, all at once. Read [P] macro, for details. An excerpt:
Local macros exist solely within the program or do-file in which they
are defined. If that program or do-file calls another program or
do-file, the local macros previously defined temporarily cease to
exist, and their existence is reestablished when the calling program
regains control. When a program or do-file ends, its local macros are
permanently deleted.
A common reason why your command sometimes "does not work" is that you ran your do-file line by line, rather than all in one go. A local macro is local to a session (hence the name). So if you ran the line local allvar a b c d e, then that will create that local macro and let it disapear as soon as Stata finished running that section of your .do file. There are two solutions:
You can get into the habit of running the definition of local macros and their use in one go. It is actually good practice to make many small .do files and make each .do file self-contained (see for example this excellent book), so you can easily just run the entire .do file each time you want to check or change something.
Alternatively, you can use global macros. These continue to exist after a session. As someone that programs in Stata, using global macros hurts my eyes, but I guess that if you use Stata only to analyse data it does little harm.
As an asside, allvar does not seem like a right name for that local macro: it does not contain all variables as it excludes the variable f. This sounds pedantic (and it is), but it is good practice to use names that accurately describe its content. In a real project we tend to come back to it after some time. A common scenarion is that you submitted a paper to a journal, it took half a year or more for the reviews to come in, and now you need to "read" your own .do-file to understand what you did half a year ago. At that point you are very happy that you were pedantic when writing the .do file...
As a further asside, assuming that a b c d e f are indeed all the variables in your dataset you can also create your local using:
ds f, not
local rhs `r(varlist)' // rhs short for right-hand side
I have written a finite volume model. The parameter n represents the number of volumes. After translating, the parameter can't be modified. Dymola gives this message:
Warning: Setting n has no effect in model.
After translation you can only set literal start-values and non-evaluated parameters.
I think the problem is that the parameter n is used in the equation section. There I use the following code:
equation
...
for i in 2:n-1 loop
T[i] = some equation
end for
I also use n for the calculation of the initial values of T.
The purpose is to make a script that repeatedly executes the model but with a different n.
How can I do this?
The issue here is that your parameter n affects the number of variables in the problem. Dymola (and all other Modelica compilers I know of) evaluate such parameters at compile time. In other words, they hard code the value at compile time into the model.
One potential workaround in your case is to perform the translation or simulation inside your loop. Note that in the translate and simulate commands in Dymola you can include modifications. Just add them after the model name. For example MyModel would become MyModel(n=10).
I am working on fairly large Mathematica projects and the problem arises that I have to intermittently check numerical results but want to easily revert to having all my constructs in analytical form.
The code is fairly fluid I don't want to use scoping constructs everywhere as they add work overhead. Is there an easy way for identifying and clearing all assignments that are numerical?
EDIT: I really do know that scoping is the way to do this correctly ;-). However, for my workflow I am really just looking for a dirty trick to nix all numerical assignments after the fact instead of having the foresight to put down a Block.
If your assignments are on the top level, you can use something like this:
a = 1;
b = c;
d = 3;
e = d + b;
Cases[DownValues[In],
HoldPattern[lhs_ = rhs_?NumericQ] |
HoldPattern[(lhs_ = rhs_?NumericQ;)] :> Unset[lhs],
3]
This will work if you have a sufficient history length $HistoryLength (defaults to infinity). Note however that, in the above example, e was assigned 3+c, and 3 here was not undone. So, the problem is really ambiguous in formulation, because some numbers could make it into definitions. One way to avoid this is to use SetDelayed for assignments, rather than Set.
Another alternative would be to analyze the names in say Global' context (if that is the context where your symbols live), and then say OwnValues and DownValues of the symbols, in a fashion similar to the above, and remove definitions with purely numerical r.h.s.
But IMO neither of these approaches are robust. I'd still use scoping constructs and try to isolate numerics. One possibility is to wrap you final code in Block, and assign numerical values inside this Block. This seems a much cleaner approach. The work overhead is minimal - you just have to remember which symbols you want to assign the values to. Block will automatically ensure that outside it, the symbols will have no definitions.
EDIT
Yet another possibility is to use local rules. For example, one could define rule[a] = a->1; rule[d]=d->3 instead of the assignments above. You could then apply these rules, extracting them as say
DownValues[rule][[All, 2]], whenever you want to test with some numerical arguments.
Building on Andrew Moylan's solution, one can construct a Block like function that would takes rules:
SetAttributes[BlockRules, HoldRest]
BlockRules[rules_, expr_] :=
Block ## Append[Apply[Set, Hold#rules, {2}], Unevaluated[expr]]
You can then save your numeric rules in a variable, and use BlockRules[ savedrules, code ], or even define a function that would apply a fixed set of rules, kind of like so:
In[76]:= NumericCheck =
Function[body, BlockRules[{a -> 3, b -> 2`}, body], HoldAll];
In[78]:= a + b // NumericCheck
Out[78]= 5.
EDIT In response to Timo's comment, it might be possible to use NotebookEvaluate (new in 8) to achieve the requested effect.
SetAttributes[BlockRules, HoldRest]
BlockRules[rules_, expr_] :=
Block ## Append[Apply[Set, Hold#rules, {2}], Unevaluated[expr]]
nb = CreateDocument[{ExpressionCell[
Defer[Plot[Sin[a x], {x, 0, 2 Pi}]], "Input"],
ExpressionCell[Defer[Integrate[Sin[a x^2], {x, 0, 2 Pi}]],
"Input"]}];
BlockRules[{a -> 4}, NotebookEvaluate[nb, InsertResults -> "True"];]
As the result of this evaluation you get a notebook with your commands evaluated when a was locally set to 4. In order to take it further, you would have to take the notebook
with your code, open a new notebook, evaluate Notebooks[] to identify the notebook of interest and then do :
BlockRules[variablerules,
NotebookEvaluate[NotebookPut[NotebookGet[nbobj]],
InsertResults -> "True"]]
I hope you can make this idea work.