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--- tutorials:sensitivity-analysis-using-grolink-and-gror [2024/06/25 15:00] – thomas
+++ tutorials:sensitivity-analysis-using-grolink-and-gror [2024/07/01 12:39] (current) – [Example: Morris Screening using the sensitivity package] thomas
@@ Line 1: / Line 1: @@
 ====== Sensitivity analysis on GroIMP models using GroR ======
-This wiki explains how to do a sensitivity analysis on GroIMP models using the GroR interface using a Morris screening over input parameters of the [[https://wwwuser.gwdguser.de/~groimp/grogra.de/gallery/CoursesAndTutorials/simpleFSPM/dirindex.html | "Example08" FSPM model]] from the gallery as an example.
+This wiki explains how to do a sensitivity analysis on GroIMP models using the GroR interface using a Morris screening over input parameters of the [[http://134.76.18.36/wordpress/courses-and-tutorials/simplefspm/ | "Example08" FSPM model]] from the gallery as an example.
 ===== Prerequisites =====
 Make sure to [[:tutorials:getting-started-with-grolink-and-gror|set up GroR]]. Play a bit around with it and get a feel for how it works and what the [[https://gitlab.com/grogra/groimp-utils/rapilibrary#grolink|different functions]] do and what they return. The approach presented in the wiki here is just one way you could approach a sensitivity analysis. You will likely find your own approach for your specific model, but GroR will be the space you work in.
+==== Downloads ====
+  * {{ :tutorials:example08_prepared.zip | Prepared Example08 model}}
+  * {{ :tutorials:example08_analysis.zip | R Script of this wiki and model outputs as .rds}}
 ===== Prepare your model=====
@@ Line 33: / Line 37: @@
 		lf[al] = lm.getAbsorbedPower3d(lf).integrate()*2.25;
 		lf.(setShader(new AlgorithmSwitchShader(new RGBAShader((float) lf[al]/5.0f, (float) lf[al]*2, (float) lf[al]/100.0f), GREEN)));
-		//println(lf[al]);
 		lf[as] = (lf[al]*86400*2)/1000000.0f;
 		lf[age]++;
@@ Line 66: / Line 69: @@
 ==== POI definition and output communication ====
+The ''Example08'' model in its default way of existing grows a plant and lets it flower. Obvious interesting outputs are the sum of absorbed light by the leaves and the amount of produced assimilates. However, this model has no defined end, it could run forever (even tho nothing really happens in the later stages).
+For this example, I decided that the interesting output would be the total absorbed light by the leaves at the point when the first flower emerges. Because you can conveniently grab the output on the console in GroR, I added some code in the ''grow()'' method to communicate both the existence of flowers and the amount of absorbed light:
+<code java>
+if(count((*NiceFlower*)) > 0){
+		println(sum((* Leaf *)[al]));
+	} else {
+		println("no flower");
+	}
+</code>
+So, after every ''grow()'' iteration, the model prints ''no flower'' as long as there are no flowers and a number for the amount of absorbed light once there is a flower.
@@ Line 71: / Line 87: @@
 ===== Model execution and output gathering in R=====
+I will first demonstrate the concept by gathering the output (the amount of absorbed light) from just one model execution (run).
+First, load some libraries and set up the workbench with the prepared model:
 <code R>
-source("path/to/GroR.R")
+source("D:\\groimp\\rapilibrary\\R\\GroR.R") # load GroR
-...
+library(future)
+library(future.apply)
+library(sensitivity)
+wb1 <- GroLink.open("http://localhost:58081/api", path="Example08.gsz") # copy gsz to groimp path
 </code>
+You can make sure that everything works by looking up the available model functions or reading the parameter file:
+<code R>
+(functions <- WBRef.listRGGFunctions(wb1))
+WBRef.getFile(wb1, "param/parameters.rgg")
+</code>
+Now here is the code that gets the model output. It executes the ''grow()'' method until it receives a console output that is not ''no flower'', meaning that there is some number for the amount of light available. When creating these kind of functions, it usually makes sense to define some kind of timeout (here 200 ''grow'' executions) because you never know if your model will actually work correctly with some weird parameter combinations you might give to it.
+<code R>
+model_output <- ""
+n_grows <- 0
+while (!(is.numeric(model_output)) && (n_grows < 200)) {
+  result <- WBRef.runRGGFunction(wb1,"grow")
+  model_output <- unlist(result$console)
+  if (model_output != "no flower"){
+    model_output <- as.numeric(model_output)
+  }
+}
+</code>
 ===== Example: Morris Screening using the sensitivity package =====
+The Morris Screening will be used to analyze the 5 structural plant growth parameters with regard to their importance (their main and interaction effect) on the total amount of absorbed light by leaves. This is just a random example out of the plethora of available sensitivity analysis methods. Most of the common ones are implemented in the ''sensitivity'' R-package. This is not a tutorial on ''sensitivity'', but it is very well documented (e.g. in the R help function). It is worth noting that this example uses the so-called decoupled approach of ''sensitivity'', see ''?tell''. This basically means that the generation of the parameter set, model execution and output analysis will be done as separate steps.
+First, I generate a set of input parameters for the model:
+<code R>
+m <-    morris(model = NULL, factors = c("NormalInternodeLength", # baseline is 0.1
+                                         "FlowerInternodeLength", # baseline is 0.05
+                                         "LeafLength",            # baseline is 0.1
+                                         "LeafAspectRatio",       # baseline is 0.7
+                                         "PlantWideness"),        # baseline is 0.1
+               r = 20,                                                 # 20 repetitions
+               binf = c(0.05, 0.01, 0.05, 0.1, 0.1),                   # min value of inputs
+               bsup = c(0.8, 0.1, 1, 1, 1),                            # max value of inputs
+               design = list(type = "oat", levels = 6, grid.jump = 3)) # 6 levels per parameter (check with e.g. length(unique(x$X[,4])))
+                                                                       # grid.jump is recommended to be levels/2, see ?morris
+params <- m$X
+</code>
+''params'' is now a 120-row matrix. In order to be able to loop over the matrix rows, I need a function that takes one parameter set as input, executes the model and returns the output for this set:
+<code R>
+executeModel <- function(params, timeout = 200){
+  wb1 <- GroLink.open("http://localhost:58081/api", path="Example08.gsz")
+  WBRef.updateFile(wb1, "param/parameters.rgg",
+                   paste("static float NormalInternodeLength = ", as.character(params[1]),
+                         ";\r\nstatic float FlowerInternodeLength = ", as.character(params[2]),
+                         ";\r\nstatic float LeafLength = ", as.character(params[3]),
+                         ";\r\nstatic float LeafAspectRatio = ", as.character(params[4]),
+                         "; \r\nstatic float PlantWideness = ", as.character(params[5]),
+                         ";",
+                         sep = ""))
+  WBRef.compile(wb1)
+  model_output <- ""
+  n_grows <- 0
+  while (!(is.numeric(model_output)) && (n_grows < timeout)) {
+    result <- WBRef.runRGGFunction(wb1,"grow")
+    model_output <- unlist(result$console)
+    if (model_output != "no flower"){
+      model_output <- as.numeric(model_output)
+    }
+    n_grows <- n_grows + 1
+  }
+  if (n_grows == timeout) {
+    model_output <- NA
+  }
+  WBRef.close(wb1)
+  return(model_output)
+}
+</code>
+This function contains the while-loop from above but also modifies (overrides) the ''parameters.rgg'' file. The ''paste()'' function is used to create the file content. The function also opens and closes a new workbench with every time it is called, this is needed to be able to parallelize model executing using the ''future'' framework:
+<code R>
+plan(multisession, workers = availableCores())
+system.time(model_outputs <- future_apply(params, 1, executeModel))
+saveRDS(model_outputs, "example08_morris_outputs.rds")
+</code>
+Through the use of ''future_apply'' and the way the ''multisession'' is setup, you will run one instance of GroIMP on every core of your computer. With this ''Example08'' model, this can take some time, on my 20-core machine it took around 2 minutes (and used ~5Gb RAM). This simple parallelization could likely be optimized a lot and will not scale amazingly to e.g. a remote cluster.
+The only thing remaining is to analyze the output and plot the results:
+<code R>
+sensitivity::tell(m, model_outputs)
+plot(m)
+</code>
+This should now look something like this:
+{{:tutorials:rplot.png?500|}}