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Read and use data from txt file
Read and use data from txt file
Hi all,
Let's say I have a simple model: y = a*t+b
Where:
t is the time
a is a variable that is read from a txt file, which depend on time.
b is a fixed parameter
model simple
constant Real b=1;
Real a,y
equation
y = a*time+b;
end simple;
now I have the txt file looking like:
t a
0 1.0
5 1.1
11 1.0
17 0.9
...
I would like to launch a simulation taking the values from txt file (with linear interpolation between values for a continuous time simulation).
Is there a example on this topic somewhere ?
Thanks in advance,
Sam
Thank you
Re: Read and use data from txt file
Use external C or Modelica.Blocks.Tables and be prepared to swear a lot
- sjoelund.se
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- 1700 Posts
Re: Read and use data from txt file
Hello Sam,
see:
https://openmodelica.org/index.php/forum/topic?id=389
https://openmodelica.org/index.php/forum/topic?id=404
Greetings, Christian
Re: Read and use data from txt file
Hi there,
although this topic is a year ago, this might help someone.
I did swear a lot about TimeTable and CombiTable when reading a file with multiple columns.
Everytime I only got the all timesteps for first item y[1], but not the rest of them, y[2:n]
Important is
1. to define the parameter "columns" with either the number of values you want to read, or a real big number to read all of them
2. if youf don't want interpolation, but the real values, you have to set simulation parameters starttime=1, stoptime <= number of time steps in your data files
My example data file "data01.txt" :
Code:
#1
double tab1(6,3) # comment line
0 0 0
1 2 5
2 4 7
3 5 8
4 6 9
5 7 10
My Model
Code:
model TestCombiTable
Modelica.Blocks.Sources.CombiTimeTable combiTimeTable(
tableOnFile=true,
fileName="c:/data01.txt",
tableName="tab1",
columns=2:1000 // put a big number at the end here
)
end TestCombiTable;
Simulation using e.g. OMNotbook:
Code:
loadModel(Modelica);
simulate(TestCombiTable,startTime=1,stopTime=6)
Check the values e.g. OMNotebook
Code:
val(TestCombiTable.y[2],{1:6})Result:
{{5.0,7.0,8.0,9.0,10.0,11.0}}
Maybe this helps someone else a bit of heavy swearing.
Greetings,
Uwe
- uschoene
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