I am a new bee to Automation and Java. I am working on a problem which requires me to read the read time stock market data from the database and verify it with the same with the value seen on the UI. I am ok having approximations up to 5% in the value. To verify if these tests have passed its important for me to assert the values with the value in the UI.
I have a small logic to verify these values, I wanted to know if this is a good way of coding on java or do i have a better way to achieve these results.
Alorigthm.
I read the int/float value from db.
Calculate 5% of the value in step 1.
Get the value in the UI and assert if its greater then or equal to value in step 2.
If greater i say Asseert.assertEquals(true,true) else i fail my assert.
If any better way to work for these values, request a better answer.
It's more usual to have your Assertion represent the meaning of your test, having to assert(true, true) does not do this. So:
3. Calculate the absoluete difference between the value obtained in step 1 and the UI value (when I say absolute value, you need to remember that the UI might be higher or lower than the db value, you need to make the difference to be always positive)
4. Assert.assertThat( difference < theFivePercentValue)
Also you could consider using the Hamcrest extension to JUnit that includes a closeTo() method.
Related
I am using the WEKA API weka-stable-3.8.1.
I have been trying to use J48 decision tree(C4.5 implementation of weka).
My data has around 22 features and a nominal class with 2 possible values : yes or no.
While evaluating with the following code :
Classifier model = (Classifier) weka.core.SerializationHelper.read(trainedModelDestination);
Evaluation evaluation = new Evaluation(trainingInstances);
evaluation.evaluateModel(model, testingInstances);
System.out.println("Number of correct predictions : "+evaluation.correct());
I get all predictions correct.
But when I try these test cases individually using :
for(Instance i : testingInstances){
double predictedClassLabel = model.classifyInstance(i);
System.out.println("predictedClassLabel : "+predictedClassLabel);
}
I always get the same output, i.e. 0.0.
Why is this happening ?
If the provided snippet is indeed from your code, you seem to be always classifying the first test instance: "testingInstances.firstInstance()".
Rather, you may want to make a loop to classify each test instance.
for(Instance i : testingInstances){
double predictedClassLabel = model.classifyInstance(i);
System.out.println("predictedClassLabel : "+predictedClassLabel);
}
Should have updated much sooner.
Here's how I fixed this:
During the training phase, the model learns from your training set. While learning from this set it encounters categorical/nominal features as well.
Most algorithms require numerical values to work. To deal with this the algorithm maps the variables to a specific numerical value. longer explanation here
Since the algorithm has learned this during the training phase, the Instances object holds this information. During testing phase you have to use the same Instances object that was created during training phase. Otherwise, the testing classifier will not correctly map your nominal values to their expected values.
Note:
This kind of encoding gives biased training results in Non-tree based models and things like One-Hot-Encoding should be used in such cases.
Suppose I input to WEKA some dataset and set a normalization filter for the attributes so the values be between 0 and 1. Then suppose the normalization is done by dividing on the maximum value, and then the model is built. Then what happens if I deploy the model and in the new instances to be classified an instance has a feature value that is larger than the maximum in the training set. How such a situation is handled? Does it just take 1 or does it then take more than 1? Or does it throw an exception?
The documentation doesn't specify this for filters in general.So it must depend on the filter. I looked at the source code of weka.filters.unsupervised.attribute.Normalize which I assume you are using, and I don't see any bounds checking in it.
The actual scaling code is in the Normalize.convertInstance() method:
value = (vals[j] - m_MinArray[j]) / (m_MaxArray[j] - m_MinArray[j])
* m_Scale + m_Translation;
Barring any (unlikely) additional checks outside this method I'd say that it will scale to a value greater than 1 in the situation that you describe. To be 100% sure your best bet is to write a testcase, invoke the filter yourself, and find out. With libraries that haven't specified their working in the Javadoc, you never know what the next release will do. So if you greatly depend on a particular behaviour, it's not a bad idea to write an automated test that regression-tests the behaviour of the library.
I have the same questions as you said. I did as follows and may this method can help you:
I suppose you use the weka.filters.unsupervised.attribute.Normalize to normalize your data.
as Erwin Bolwidt said, weka use
value = (vals[j] - m_MinArray[j]) / (m_MaxArray[j] - m_MinArray[j])
* m_Scale + m_Translation;
to normalize your attribute.
Don't forget that the Normalize class has this two method:
public double[] getMinArray()
public double[] getMaxArray()
Which Returns the calculated minimum/maximum values for the attributes in the data.
And you can store the minimum/maximum values. And then use the formula to normalize your data by yourself.
Remember you can set the attribute in Instance class, and you can classify your result by Evaluation.evaluationForSingleInstance
I 'll give you the link later, may this help you.
Thank you
I need to look for all web requests received by Application Server to check if the URL has extensions like .css, .gif, etc
Referred how tomcat is listening for every request and they pick the right configured Servlet to serve.
CharChunk , MessageBytes , Mapper
Here is my idea to implement:
Load all the extensions we like to compare and get the byte
representation of them.
get a unique value for this xtension by summing up the bytes in the byte Array // eg: "css".getBytes()
Add the result value to Sorted List
Whenever we receive the request, get the byte representation of the URL // eg: "flipkart.com/eshopping/images/theme.css".getBytes()
Start summing the bytes from the byte array's last index and break when we encounter "." dot byte value
Search for existence of the value thus summed with the Sorted List // Use binary Search here
Kindly give your feed backs about the implementation and issues if any.
-With thanks, Krishna
This sounds way more complicated than it needs to be.
Use String.lastIndeXOf to find the last dot in the URL
Use String.substring to get the extension based on that
Have a HashSet<String> for a set of supported extensions, or a HashMap<String, Whatever> if you want to map the extension to something else
I would be absolutely shocked to discover that this simple approach turned out to be a performance bottleneck - and indeed I suspect it would be more efficient than the approach you suggested, given that it doesn't require the entire URL to be converted into a byte array... (It's not clear why your approach uses byte arrays anyway instead of forming the hash from char values.)
Fundamentally, my preferred approach to performance is:
Do up-front design and testing around things which are hard to change later, architecturally
For everything else:
Determine the performance criteria first so you know when you can stop
Write the simplest code that works
Test it with realistic data
If it doesn't perform well enough, use profilers (etc) to work out where the bottleneck is, and optimize that making sure that you can prove the benefits using your existing tests
I asked a question How to get an Integer as result?
The suggested solution with decimalFormat works, but my problem is that I want my data not only to be presented as ##.0 but to be like this, because in the end of my program I use them. So I want to be exactly in that type; otherwise I get the wrong final number. Any ideas?
EDIT:
let me be more specific. i get 12,344 from my first calc, 14,4566 from my second and 18,5644 from my third.that makes a sum 45.365.Now,if i do then 12,3 , 14,4 and 18,5 the sum is 45.2...thats the point of my answer.i want to have 45.365 at the end and not 45.2
The problem seems to be a design issue with your app.
On the one hand, you want to display the results to the user with 1 digit after the decimal point.
In the other hand, you actually want to keep the extra precision and use it for follow-up calculations.
I would argue that this is a poor user interface model. IMO, the numbers that the user sees should be the numbers that go into the calculations. This means you should either:
show the user more digits after the DP in the first place (or at least give a visual indication that there are more digits), or
do the calculations using the rounded / truncated values ... as displayed to the user.
Once you have figured out a consistent user interface model, the required implementation approach should be much clearer to you.
I have a question which is described below:
What problems would arise for testing a Java class which counts number of words in a file?
The function's signature is below:
public int wordCount(String filename)
Well, this is a junit testing question.
If you know the problem, what is the solution of that?
So your question is what to test for? If yes, I'd say you should check if the definition of "word" is implemented correctly (e.g. is "stack-overflow" one word or two), are new lines handled correctly, are numbers counted as words (e.g. difference between "8" and "eight"), are (groups of special) characters (e.g. a hyphen) counted correctly.
Additionally, you should test whether the method returns the expected value (or exception) if the file does not exist.
This should be a good starting point.
To sfussenegger's list, I'd add the file handling checks: does the method respond correctly to files not found (including null filename), or lacking read permission?
Also, to sfussenegger's correctness list, I'd add whether duplicates count and case sensitivity rules, as well.
Of course, all of this requires that you know how the method is supposed to behave for all of these specifics. It's easy to tell someone to "go count words", but there are subtleties to that assignment.
Which is one of the big benefits of writing a good set of unit tests.
This really sounds like a task for FIT: Framework for Integrated Test. It's an acceptance testing framework that works with ant and JUnit.
One docent of mine did such a task and used this framework. It allows you to write a whole bunch of test cases within one html/wiki table. FIT will interpret each line as a parameter set for the function under test and checks the output.
For example:
This table displays the result of three test cases. Two passed, one failed.
You can use fit if you write sentences and define the number of words in your table. With FIT, they're executed and the result is displayed in a new table.
For further information, please read Introduction to FIT.