# suggestion needed for running a model in a NB1 while data is imported from NB2

I want to iteratively run a set of scenarios. There are two notebooks NB1 and NB2. The former includes the following system of 2 equations, and the latter includes data and parameter specifications for scenarios. NB1 is:

a X1 + b Y1 == A1;
c X1 + d Y1 == B1;


where {A1, B1} is the set of constants, and {a, b, c, d} is the set of parameters calculated in NB2.

In the notebook NB2, I keep the data and parameters (scenarios):

benchmarkData = {A1=3, B1=7, a=2, b=9, c=5, d=4};
scenario[i]   = {A1=1, B1=0, a=1, b=8, c=5, d=4};


In NB1, I also created a matrix of 8 by 6 in order to store the solutions from i=6 scenarios. The first column is reserved for storing the solution from i=1 in the order of sol = {X1, Y1, A1, B1, a, b, c, d}. I first run NB2 to define benchmarkData and scenario[i], and then go to NB1 to Get["file director of NB2"] the defined benchmark and scenario variables into NB1 and run the model. When the solution is obtained, store it to the first column of the scenario matrix created in NB1. I repeat the same procedure for each new scenario: design a new scenario in NB2, go to NB1 to run the model and store the solution in the 2nd column of the matrix, etc.

I know how to do this operation in a single notebook by using:

While[z<7, {the model and the matrix}; z++]


but I could not do the same iteration using two separate notebooks. This is a simple version of a very big model with a large dataset. That is why I had to divide the code into two notebooks to iteratively run the scenarios and get a matrix of solutions.

I tried several ways to achieve the task such as creating an index z in NB2 and store the solution in NB1 with an indexed variable but it did not work because the code always kept the very last scenario run not the earlier ones.

I am likely missing the point, but why not store the scenarios (NB2) in a simple text file, one record per line.

3 7 2 9 5 4
1 0 1 8 5 4


You can then read the whole file from NB1 as a list, an assign values to variables in a loop.

a X1 + b Y1 == A1;
c X1 + d Y1 == B1;

Number, RecordLists -> True,
RecordSeparators -> {"\n", "\r\n", "\r"}];

z = 1;
While[z <= Length[data],
A1 = data[[z, 1]];
B1 = data[[z, 2]];
a = data[[z, 3]];
b = data[[z, 4]];
c = data[[z, 5]];
d = data[[z, 6]];

Echo[Solve[a X1 + b Y1 == A1 && c X1 + d Y1 == B1, {X1, Y1}]];

z++;
]


Here are the results for these two entries:

{{X1->51/37,Y1->1/37}}

{{X1->-(1/9),Y1->5/36}}

• One of the reasons why I like to run an iterative procedure is that I have many different scenarios and I did not want to keep all these scenarios in a separate text file. Instead, I just want to change few parameters in NB1 and run the model in NB2 and see the results immediately in the predefined table. Another reason is that I wanted to store the results from each scenario as a column vector of an output matrix created in NB2. Thank you so much for your suggestion. May 7, 2020 at 23:28

Here is a solution to the above problem.

When you add the following code at the end of NB2, each time you run the model with a different parameter set, the results are saved in a file created by OpenAppend[...]. New runs are appended to the previous set of results.

(*First create a file to keep the results obtained from each run*)

ESTgrowth = FileNameJoin[{"directory to keep the file", "ESTgrowth"}];
open = OpenAppend[ESTgrowth];
Write[open, newsolution];  (*newsolution is the results from a model run that you want to keep.*)
Close[open];
EST = FilePrint[ESTgrowth]
(*use DeleteFile[ESTgrowth] to delete the file from the
directory concerned*)


This is a very convenient way of running a given model for different parameters without making any change in the model variables. Moreover, the results are nicely kept in a separate file that can be used in other calculations without needing to run the model again.