Getting started with FaultTree on R
openreliability.org/faulttree-users-tutorial/start-faulttree-on-r
FaultTree User's Tutorial
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This introduction will cover installation of R and the FaultTree package. R has been
selected as the container environment for this open source Fault Tree Analysis software. R
is an excellent prototyping environment, although it is not known for its user friendliness.
This introduction will hopefully get tentative users off to a running start. Although R is
multi-platform environment, this introduction will be made from a Windows user
perspective.
A Windows installer for the R environment is available for free download starting at:
https://www.r-project.org/
Select the download link, then choose a mirror (the first selection always works for me).
Here you will view the download links for the three supported operating systems. It does
not matter which version of Windows you are using. On a 32-bit installation you will get a
32-bit R system. On a 64-bit system you will get both the 32-bit and the 64-bit
installation. Don't worry it doesn't really matter which one you use. We are only
concerned with a base installation, click on the 'install R for the first time' link.
It is fine to install with default conditions, however, this creates an MDI application where
multiple instances can run in a single container. I find this uncomfortable and prefer the
SDI format. Want to try again? Uninstall through the ControlPanel and re-run the
installer. This time select a 'custom installation', which will give you a chance to install the
SDI format. All the other defaults are fine.
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I should mention here that there is a further
developer environment that some prefer called R
Studio. This application gives an unabashed look
and feel of MatLab to R. This is also available as a
free download at:
https://www.rstudio.com/products/RStudio/
The remainder of this introduction will refer to the simplest R SDI installation. Really we
don't need to know much about the R programming language to use FaultTree. Most
people find R to have a very steep learning curve, largely due to the stark terminal window
that it opens up to. This introduction hopes to guide any first-time user to success.
FaultTree is a package that must be loaded into R. The package is hosted at R-Forge:
https://r-forge.r-project.org/
From that location navigation would be required by search of Project - ftree. From that
location one must select the R Packages link just below the Fault Tree and Event Tree
Analysis title button. Or for those in a rush, just load the following URL: https://r-forge.rproject.org/R/?group_id=2125
Yes, there is more than one package addressed here. We of course want FaultTree. There
are two ways to load this package into your R installation I will walk through both. You
can download the .zip file next to the Windows logo. But, do not unzip this as one
might expect! Rather, we will open this using the R environment. Run an R instance as administrator. This is usually accomplished by right clicking on the icon and
selecting 'Run as administrator'. I prefer this since only the administrator can load the
package into the main R installation, rather than a separate user library. This is a bit of
Linux legacy, but we now have users separate from administrator on Windows since
Windows 7. Now, in the R Console select the Packages menu item. Then at the bottom of
the dropdown menu select 'Install package(s) from local zip files…' Navigate to the
location of the downloaded zip from R-forge and open it in R. You should see the
following confirmation in the R Console:
> utils:::menuInstallLocal()
package ‘FaultTree’ successfully unpacked and MD5 sums checked
>
Before continuing, I will mention perhaps an easier method of installation. R-forge
provides an automated download and installation command line just underneath the
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Linux and Windows icons with (.tar.gz) and (.zip) respectively. Generally from the latest
version of R (that's what you have if you just downloaded for the first time) -as
administrator - you should be able to just copy and paste the installation command
directly into the R Console:
install.packages("FaultTree", repos="http://R-Forge.R-project.org")
[I once tried this with R version 3.3.1 and it did not work because R-Forge had not
gotten around to updating the package build (at version 0.0.9) since R version 3.3.0 . So
I got a warning (failure) message for this reason. However the earlier zip method works
on all versions.]
This installation operation is only performed once per version of the package. From this
point we can use the FaultTree package on each session of R by just mounting the library,
which has already been installed in your local file system. This is done by the simple
command line directly into the R Console:
library(FaultTree)
This command line only needs to be executed once each R session. That is you can simply
open either the 32-bit or the 64-bit R icon by double click and enter this library entry. You
may get a warning about the package built under a different R version, but this is only a
warning of no significance. There is no harm in making the library call repeatedly, it is
just not necessary. Some example scripts might include the library line, perhaps as just a
reminder.
To conclude this introduction we will run an example. Copy and paste this script code
into the R Console:
tree1 <- ftree.make(type="priority",reversible_cond=TRUE, name="Site power loss")
tree1 <- addLogic(tree1, at=1, type="or", name="neither emergency", name2="generator
operable")
tree1 <- addLogic(tree1, at=2, type="and", name="Independent failure", name2="of
generators")
tree1 <- addLatent(tree1, at=3, mttf=5,mttr=12/8760,inspect=1/26, name="e-gen
set fails")
tree1 <- addLatent(tree1, at=3, mttf=5,mttr=12/8760,inspect=1/26, name="e-gen
set fails")
tree1 <- addLogic(tree1, at=2, type="inhibit", name="Common cause", name2="failure of
generators")
tree1 <- addProbability(tree1, at=6, prob=.05, name="Common cause", name2="beta
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factor")
tree1 <- addLatent(tree1, at=6, mttf=5,mttr=12/8760,inspect=1/26, name="e-gen
set fails")
tree1 <- addDemand(tree1, at=1, mttf=1.0, name="External power",
name2="interruption")
tree1 <- ftree.calc(tree1)
tree1[,1:8]
You should see a tabular output of the tree. This is a partial view of the dataframe used to
hold the fault tree. For a graphic view it is necessary to write an html file that will then be
opened in the default browser. The default location for this file should be the Documents
library on Windows.
ftree2html(tree1, write_file=TRUE)
browseURL("tree1.html")
Now the image below should appear in your default browser.
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