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Questions tagged [modeling]

Modeling is the constructing and manipulating abstract (mathematical and/or graphical) representations of economic, engineering, manufacturing, social, and other types of situations and natural phenomenon, simulated with the help of a computer system.

Modeling is the construction and manipulation of abstract (mathematical and/or graphical) representations of economic, engineering, manufacturing, social, and other types of situations and natural phenomenon, simulated with the help of a computer system.

2023 questions
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Anylogic. Modelling proccess lib. Connections between stock elements (like Source or Queue) with custom classes

I have some troubles with finding a way to connect a Queue's exit with the enter point of the Sink, which is INSIDE my own custom agent. I'm trying to make a model of a database system, so i have a couple of Sources (which are making queries as…
Viktor Fridman
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Can't add InputPin as a Node of an Activity (Eclipse/Epsilon)

I'm writing a model-to-model transformation at the moment. Here is a part of my ETL file: rule process2activity transform p : input!Process to a : UMLOutput!Activity{ ... var ip : new UMLOutput!InputPin; …
ramy
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Anylogic 7. Databases modelling

I am looking for the best way to model a database system. It should be made of nodes, edges and data query flows. I know there is a flow lib, but i dont sure that it is usable for such things. So, the question is: is there any libs that i could use…
Viktor Fridman
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Is this the correct way to forecast stock price volatility using GARCH

I am attempting to make a forecast of a stock's volatility some time into the future (say 90 days). It seems that GARCH is a traditionally used model for this. I have implemented this below using Python's arch library. Everything I do is explained…
KOB
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How to define a set of paths, or set of sequences of links, in AMPL?

I'm trying to define a structure to capture something like below: set NODES := A B C; set LINKS := (A,B) (B,C); set PATHS := ((A,B)) ((A,B), (B,C)) ((B,C)); Nodes are a set. Links are a set of node pairs. I am having…
Matt Hall
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Why might python override the values associated with a dictionary key which has not been called?

My script is overriding values associated with keys/a key that hasn't been called. I have a nested dictionary containing a hierarchy of keys like: dict["species"]["type"]["reaction"] This is a copy of another dictionary (dict_0 lets say) with the…
ratchet600
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Model-to-Model-Transformation - no meta model for source

I have to do a model-to-model transformation but the source model is rather obscure but also quite similar to UML activity diagrams (which are also the target by the way). I've looked into tutorials for Eclipse Modeling Tools but I struggle a lot…
ramy
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Measuring influence in lme4

I am currently doing mixed effects model analysis for a university project. I am currently trying to measure potential influences in my data using the following and become stuck with this error message in R. alt.est.S <-…
twstats
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How to map different indices in Pyomo?

I am a new Pyomo/Python user. Now I need to formulate one set of constraints with index 'n', where all of the 3 components are with different indices but correlate with index 'n'. I am just curious that how I can map the relationship between these…
Gabriel Yin
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popbio - Why isn't it reading my fertility column

I wanna do bootstrapping on my data using popbio's boot.transitions function. However, it is somehow giving a weird error with the fertility column: stagefate = read.table("file.csv", header = TRUE, sep=",") stagefatenames<- c("individual", "stage",…
Kaiser
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Generate Interaction Terms with SAS Proc Logistic for Large Datasets

Performing logistic regression with large number of explanatory variables (400 in this example). I can easily reference all 400 variables using the code below in the model statement, but is there also an easy way to generate 1st level interaction…
krohn
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Filtering OrganizationUser's by Organization in Django-Organizations

There is a relatively similar thread on this topic, but I can't seem to figure out how to translate it to my situation. I have a roster that I need to only display the organizationusers within the same organization of the viewer. I have a webapp…
Ethan Thompson
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R package Ranger produces errors related to variable "none"

I am using the Ranger package in R to create a classification model of text. However, when one of the variables is "none", I get the following error. Error in intI(j, n = x@Dim[2], dn[[2]], give.dn = FALSE) : index larger than maximal 5002 I…
Jonno Bourne
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Why is my third MATLAB function outputing only zeros when using ode45?

I need to model negative, positive and simple regulation of a gene for my systems biology class using MATLAB. The problem is that the functions for negative and simple regulation work but the positive regulation function is only outputting zeros.…
Annika Aguraiuja
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Object-Oriented Way of Dealing with Read-Only User Input

I'm making a simple command-line game but not sure how to model read-only user inputs in Python. Right now, I'm thinking of declaring an ABC called Input and subclassing it: import abc class Input(abc.ABC): @abc.abstractmethod def…
Bartleby
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