The Data Blog

This blog post is the first of a series of blog post on using SPMF from different programming languages. Today, I will explain how to call the SPMF data mining library from C#. In other blog posts, I explain how to call SPMF from R and how to call SPMF from Python.

Requirements

First, you should make sure that you have installed C# and Java on your computer.

Second, you should download the spmf.jar file from the SPMF website and put it in the same directory as your C# program.

Third, you should make sure that your Java installation is correct. In particular, you should be able to execute the java command from the command line of your computer. If you type “java -version” in the command line of your computer, you should see the version of Java:

If you see this, then it is OK.

If you do not see this but instead get an error that java.exe is not found, it means that you have not installed Java, or that the PATH to Java is not setup properly on your computer so you cannot use it from the command line. If you are using the Windows operating System and you have installed Java, you need to make sure that java.exe is in the PATH environment variable. On Windows 11, you can fix this problem as follows: 1) Press WINDOWS + R, 2) Run the command “sysdm.cpl“, 3) Click the Advanced system settings tab. 4) Click Environment Variables. 5) In the section System Variables find the PATH environment variable and select it. 6) Click Edit. Add the path to the folder containing java.exe, which will be something like : C:\Program Files\Java\jdk-17.0.1\bin (depending on your version of Java and where you have installed it). 7) Click OK and close all windows. Then, you can open a new command prompt and try running “java -version” again to see if the problem is fixed. If you are using another version of Windows or the Linux operating system, you can find similar steps online about how to setup Java on your computer.

1) Launching the GUI of SPMF from C#

Now that I have explained the basic requirements, I will first show you how to launch the GUI of SPMF from C#. For this, it is very simple. Here I give you the code of a simple C# program that calls the Jar file of SPMF to launch the GUI of SPMF:

using System.Diagnostics;

Process myProcess = new Process();
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.RedirectStandardOutput = true;
myProcess.StartInfo.FileName = "java";
myProcess.StartInfo.Arguments = "-jar spmf.jar"; // You could also put a path to the jar file like C:\\Users\\philippe\\Desktop\\
myProcess.Start();
myProcess.WaitForExit(); // If you want to wait for the program to terminate

What this program does? It basically just runs the command
java -jar spmf.jar

By running this C# program, SPMF is successfully launched:

2) Executing an algorithm from SPMF from a C# program

Now, let’s look at something more interesting. How can we run an algorithm from SPMF from C#? We just need to modify the above program a little bit. Let’s say that we want to run the Apriori algorithm on an input file called contextPasquier99.txt (this file is included with SPMF and can be downloaded here).

To do this, we need to first check the documentation of SPMF to see how to run the Apriori algorithm from the command line. The documentation of SPMF is here. How to run Apriori is explained here. We find that we can use this command

java -jar spmf.jar run Apriori contextPasquier99.txt output.txt 40%

to run Apriori on the file contextPasquier99.txt with the parameter minsup = 40% and to save the result to a file output.txt.

To do this from C#, we can write a C# program like this:

using System.Diagnostics;

Process myProcess = new Process();
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.RedirectStandardOutput = true;
myProcess.StartInfo.FileName = "java";
myProcess.StartInfo.Arguments = "-jar spmf.jar run Apriori contextPasquier99.txt output.txt 40%";
myProcess.Start();
myProcess.WaitForExit(); // If you want to wait for the program to terminate

Then, if we run this program in a folder that contains spmf.jar and contextPasquier99.txt, it will produce the file output.txt as result:

If we open the file “output.txt”, we can see the content:

Each line of this file is a frequent itemset found by the Apriori algorithm. To understand the input and output file format of Apriori, you can see the documentation of the Apriori algorithm.

If you want to call other algorithms that are offered in SPMF beside Apriori, you can lookup the algorithm that you want to call in the SPMF documentation to see how to run it and then change the above program accordingly.

3) Executing an algorithm from SPMF from a C# program and then reading the output file

Now let me show you another example. I will explain how to call an algorithm from an SPMF and then read the output file from a C# program.

Generally, the output of algorithms from SPMF is a text file (such as in the above example). Thus, to read the output of an SPMF algorithm from C#, you just need to know how to read a text file from a C# program.

For example, I modified the previous C# program to read the content of the file “output.txt” that is produced by SPMF to show its content in the console.

This is the modified C# program:

using System.Diagnostics;
using System;
using System.IO;

// Call Apriori
Process myProcess = new Process();
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.RedirectStandardOutput = true;
myProcess.StartInfo.FileName = "java";
myProcess.StartInfo.Arguments = "-jar spmf.jar run Apriori contextPasquier99.txt output.txt 40%";
myProcess.Start();
myProcess.WaitForExit(); // wait for the program to terminate

// Read the output file 
using(StreamReader file = new StreamReader("output.txt")) {  
 string ln;  
  
 while ((ln = file.ReadLine()) != null) {  
  Console.WriteLine(ln);  
 }  
 file.Close();  
} 

If we run the program, it will run the Apriori algorithm and then read the output file and write each line of the output file in the console:

We could further modify this program to do something more meaningful with the content of the output file. But at least, I wanted to show you the basic idea of how to read an output file from SPMF from a C# program.

3) Writing an input file for SPMF from a C# program, and then running an algorithm from SPMF

Lastly, you can also write the input file that is given to SPMF from a C# program by using code to write a text file.

For example, I will modify the example above to write a new text file called “input.txt” that will contain the following data:

1 2 3 4
2 3 4
2 3 4 5 6
1 2 4 5 6

and then I will call SPMF to execute the Apriori algorithm on that file. Then, the program will read the output file “output.txt” from C#. Here is the code:

using System.Diagnostics;
using System;
using System.IO;

// Write a file
using (StreamWriter writer = File.CreateText(@"input.txt"))
{
    writer.WriteLine("1 2 3 4");
    writer.WriteLine("2 3 4");
    writer.WriteLine("2 3 4 5 6");
    writer.WriteLine("1 2 4 5 6");
}

// Call Apriori
Process myProcess = new Process();
myProcess.StartInfo.UseShellExecute = false;
myProcess.StartInfo.RedirectStandardOutput = true;
myProcess.StartInfo.FileName = "java";
myProcess.StartInfo.Arguments = "-jar spmf.jar run Apriori input.txt output.txt 40%";
myProcess.Start();
myProcess.WaitForExit(); // wait for the program to terminate

// Read the output file 
using(StreamReader file = new StreamReader("output.txt")) {  
 string ln;  
  
 while ((ln = file.ReadLine()) != null) {  
  Console.WriteLine(ln);  
 }  
 file.Close();  
} 

After running this program, the file “input.txt” is successfully created:

And the content of the output file is shown in the console:

Conclusion

In this blog post, I have shown the basic idea of how to call SPMF from C# by calling SPMF as an external program. It is quite simple. It just require to know how to read/write files in C#.

Hope that this has been interesting.

I will later post similar tutorials for other programming languages such as Python, and R so as to make it easier to use SPMF from other languages.

==
Philippe Fournier-Viger is a full professor  and the founder of the open-source data mining software SPMF, offering more than 110 data mining algorithms. If you like this blog, you can tweet about it and/or subscribe to my twitter account @philfv to get notified about new posts.