Data import

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Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Data import

Post by Sarah8888 »

To whom it may concern

I get the following messages when I want to simulate my model:
1) ERROR: The variable- DAccompany netmigration -and perhaps others require a data file be specified.
2) ERROR:Unable to correctly load in exogenous values - aborting."

With regard to 1) This concern a variable that used "data" via the import of an excel file and hence it is specified as Data-varbible. Interestingly, if I click on the variable and display its values - there are values (e.g. in the graph) - so, I really don't understand the issue.

with regard to 2) I don't understand what is the problem: It guess it concerns variables for which I use GET XLS Constants. I use an equation as: "GET XLS CONSTANTS('Modelinputs010218.xlsx' , 'Initvalues','b3')" - and indeed, the variables are not filled with the data.

If you could please provide some advice, I will be very thankful :)
Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Re: Data import

Post by Sarah8888 »

May-be to add: If I only have variables with the equation GET XLS CONSTANTS('Modelinputs010218.xlsx' , 'Initvalues','b3')
then this function works...
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: Data import

Post by tomfid »

Have you specified your data.vdf in the data field, on the Advanced tab of the Simulation Control dialog?
Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Re: Data import

Post by Sarah8888 »

So, what I did (in case I did not use the GET XLS Constants" is the following:

1) I went to "model -> import data set -> I chose the excel file and sheet etc.
2) If e.g. I want to have the data from the Excel sheet for the variable "GDP", I simply choose the data-option in the type field.

That is all I did. Is there something missing?

Thanks again so much!
Sarah
Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Re: Data import

Post by Sarah8888 »

Dear Tom

I see if I chose the 'Sim control" go to advanced and chose then the data sheet I need for the data that is imported, the simulation runs - although, I get a lot of errors saying that there is no data imported (although, it is clear that somehow the data is used as otherwise there would be no simulation results)....
Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Re: Data import

Post by Sarah8888 »

I receive the following type of warnings (not errors):

- WARNING: Simulation starts before first time for exogenous variable - Demployed.
- WARNING: Exogenous variable - Dbirths - in range at time 1996.
- WARNING: Simulating beyond range for exogenous variable - Dbirths - at time 2014.25.

All those variables use time series data by the use of the "data-import" possibility. (and as explained early, the data is used, and I used 'interpolate' to fill the gaps if there is no data.
Administrator
Super Administrator
Posts: 4573
Joined: Wed Mar 05, 2003 3:10 am

Re: Data import

Post by Administrator »

Have you reviewed the Vensim documentation on how to use external data?
http://www.vensim.com/documentation/ind ... ?usr16.htm

I think we'd need to see the model and source data before we can advise further. The warning "Simulation starts before first time for exogenous variable " is letting you know that for example, INITIAL TIME = 0 , but your data starts at 10.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: Data import

Post by tomfid »

In the data field on the Advanced tab, you should be specifying a .vdf file that you previously imported from Excel (or from another model, .tab delimited, etc.). Listing a spreadsheet there won't work.

Warnings about "Simulation starts before first time for exogenous variable" can usually be ignored. But if you're in doubt about any of the data, you should just graph each data variable to verify it.

For a walk-through, see Chapter 16 of the User Guide: http://vensim.com/documentation/usr16.htm
Sarah8888
Junior Member
Posts: 16
Joined: Thu Feb 08, 2018 12:46 pm
Vensim version: DSS

Re: Data import

Post by Sarah8888 »

OK, many thanks!

It seems to work now (apart that from warnings)

Thanks a lot again
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