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I should check existence of values based on some conditions.
i.e. i have 3 variables, varA, varB and varC. varC should not be empty only if varA>varB (condition).
i normally use some syntax to check any of the variables and run a frequency of any of them to see if there are errors:
if missing(varC) and (varA>varB) ck_varC=1.
if not(missing(varC)) and not(varA>varB) ck_varC=2.
exe.
fre ck_varC.
exe.
I had some errors when the condition became complex and when in the condition there are missing() or other functions but i could have made a mistake.
do you think there is an easier way of doing this checks?
thanks in advance
EDIT: here an example of what i mean, think at a questionnaire with some routing, you ask age to anyone, if they are between 17 and 44 ask them if they work, if they work ask them how many hours.
i have an excel tool where i put down all variables with all conditions, then it will generate the syntax in the example, all with the same structure for all variables, considering both situations, we have a value that shouldn't be there or we don't have a value that should be there.
is there an easier way of doing that? is this structure always valid no matter what is the condition?
In SPSS, missing values are not numbers. You need to explicitly program those scenarios as well. you got varC covered (partially), but no scenario where varA or varB have missing data is covered.
(As good practice, maybe you should initialize your check variable as sysmis or 0, using syntax):
numeric ck_varC (f1.0).
compute ck_varC=0.
if missing(varC) and (varA>varB) ck_varC=1.
if not(missing(varC)) and not(varA>varB) ck_varC=2.
***additional conditional scenarios go here:.
if missing(varA) or missing(varB) ck_varC=3.
...
fre ck_varC.
By the way - you do not need any of the exe. commands if you are going to run your syntax as a whole.
Later Edit, after the poster updated the question:
Your syntax would be something like this. Note the use of the range function, which is not mandatory, but might be useful for you in the future.
I am also assuming that work is a string variable, so its values need to be referenced using quotation signs.
if missing(age) ck_age=1.
if missing(work) and range(age,17,44) ck_work=1.
if missing(hours) and work="yes" ck_hours=1.
if not (missing (age)) and not(1>0) ck_age=2. /*this will never happen because of the not(1>0).
if not(missing(work)) and (not range(age,17,44)) ck_work=2. /*note that if age is missing, this ck_work won't be set here.
if not(missing(hours)) and (not(work="yes")) ck_hours=2.
EXECUTE.
String variables are case sensitive
There is no missing equivalent in strings; an empty blank string ("") is still a string. not(work="yes") is True when work is blank ("").
I build the formula in z3 using the java API.
However, I have some formula that are difficult to solve, and I want to investigate why. Therefore, I want to print the formula in SMTLIB2 format.
Is it possible to get that from a Solver object. Currently, what I can get is only an array of assertions. Thank you.
Yes, Solver.toString() does that. This should also include the variable/constant declarations if you are using the latest master; I think that part was added after the last release.
I am using Z3py and trying to get the set of all the variables in any constraint in a Solver. I can call Solver.assertions() to get an ASTVector, then loop over this vector and get objects of type BoolRef, for example, but then I'm stuck. How can I recursively iterate over an assertion, a BoolRef instance for example, to get the individual variables?
Thanks Taylor for your answer. I think the second link addresses the question.
In more detail, the python script that Leo added in the previous answer walks an AST, the AstMap ensures that shared sub-expressions are only walked once.
I am trying to count the number of satisfying assignments by Z3. I am wondering if Z3 provides such information. If so, how can I count models in Z3 and particularly in Z3Py?
While Taylor's answer will give you the number of satisfying assignments, it will iterate over all of them. In principle, it is possible to do it without such an expensive iteration, but Z3 does not offer it.
There are efficient model counters for propositional logic, the same language used in SAT (search for sharpSAT to find such a system), but as far as I know there is no available model counter modulo theories.
No, such information is not available by default. However, you could easily implement this (assuming finite number of models) in any of the APIs by combining the model generation capability with adding assertions to prevent future assignments from being assigned the same values as past models. See the following answer for a Z3py script accomplishing this:
Z3: finding all satisfying models
To count the models, simply add a counter to the loop until it becomes unsat, and this will give you the number of models.
I am using Z3 from the API and I'm looking for a way to debug my constraints. My code compiles and Z3 runs on my constraints, but something is wrong with my constraints. I'm hoping to look at the constraints that I gave to Z3 to determine what is wrong or missing, but I'm not sure how to do this in a way that is very readable. The problem is that using facilities like SMTLIB_DUMP_ASSERTIONS does not provide meaningful names in any let bound variables. Since I have many reuses of the same expressions, nearly everything is let-bound with a generated variable.
Is there any way to dump a file of the input constraints, where let-bound variables have a name that I have assigned? I don't particularly care what the format is, but SMTLIB 1 or 2 would be nice.
No, you cannot provide names to let variables automatically created by Z3 AST printers.
One possible solution is to write your own AST printer. In the Z3 distribution, we have an example application examples/c/test_capi.c. It contains the function:
void display_ast(Z3_context c, FILE * out, Z3_ast v)
It shows how to implement a simple AST printer. This example is very simple, but it is a starting point.