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Articles on Trending Technologies
Technical articles with clear explanations and examples
What is the difference between Backtracking and Non- Backtracking?
Top-Down Parsing with BacktrackingIn Top-Down Parsing with Backtracking, Parser will attempt multiple rules or production to discover the match for input string by backtracking at every step of derivation. So, if the used production does not give the input string as needed, or it does not match with the needed string, then it can undo that shift.Top-Down Parsing without BacktrackingAs backtracking looks more powerful by which we can select different alternatives. But backtracking cannot be applied or implemented so easily in parsing. There are two types of Top-Down Parsing without Backtracking, which are as follows −Recursive Descent ParserPredictive ParserRecursive Descent ...
Read MoreFind FIRST & FOLLOW for the following Grammar.\\nS → A a A | B b B\\nA → b B\\nB → ε
SolutionComputation of FIRSTA → b B∴ FIRST(A) = {b}B → ε∴ FIRST(B) = {ε}S → A a AApplying Rule (4) of FIRSTi.e., Comparing S → A a A with X → Y1Y2Y3∴ FIRST (S) = FIRST (A a A) = FIRST (A) = {b}∴ FIRST(S) = {b}S → B b B∵ FIRST (B)contains ε or B derives ε ∴ Applying Rule (4c)∴ FIRST (S) = FIRST (B to B)∴ FIRST (S) = FIRST (B) − {ε} ∪ FIRST(bB)∴ FIRST (S) = FIRST (B) − {ε} ∪ {b} = {ε} − {ε} ∪ {b} = {b}∴ FIRST (A) = {b}FIRST (B) ...
Read MoreWhat are FIRST and FOLLOW and how they are computed?
FIRST and FOLLOW are two functions associated with grammar that help us fill in the entries of an M-table.FIRST ()− It is a function that gives the set of terminals that begin the strings derived from the production rule.A symbol c is in FIRST (α) if and only if α ⇒ cβ for some sequence β of grammar symbols.A terminal symbol a is in FOLLOW (N) if and only if there is a derivation from the start symbol S of the grammar such that S ⇒ αNαβ, where α and β are a (possible empty) sequence of grammar symbols. In ...
Read MoreWhat is a Predictive Parser?
Predictive Parser is also another method that implements the technique of Top- Down parsing without Backtracking. A predictive parser is an effective technique of executing recursive-descent parsing by managing the stack of activation records, particularly.Predictive Parsers has the following components −Input Buffer − The input buffer includes the string to be parsed followed by an end marker $ to denote the end of the string.Here a, +, b are terminal symbols.Stack − It contains a combination of grammar symbols with $ on the bottom of the stack. At the start of Parsing, the stack contains the start symbol of Grammar ...
Read MoreHow to check matrix values equality with a vector values in R?
If we have a vector called V that contains five values and a matrix say M that contains five columns and we want to check whether first value in the vector is present in the first column of each row in the matrix and so on for each value in the vector then we can use the below command −t(t(M)==V)Example 1Consider the below matrix and vector −M1
Read MoreFind the row means for columns starting with a string in an R data frame.
To find the row means for columns starting with specific string in an R data frame, we can use mutate function of dplyr package along with rowMeans function.For Example, if we have a data frame called df that contains three columns say x1_x2, x1_x3, x1_x2 and we want to find the row means for columns x1_x2 and x1_x3 then, we can use the below command −df%%mutate(X1_Cmbn=select(.,starts_with("x1_")) %% rowMeans())Example 1Following snippet creates a sample data frame −Grp1_x
Read MoreDifferent Participants of Defect Life Cycle
What Exactly is a Defect?A fault or error in an application that restricts the usual flow of the application by mismatching the expected behavior of an application with the real one is referred to as a defect.A defect happens when a developer makes a mistake when developing or constructing an application. When a tester discovers this error, it is referred to as a defect.A tester must thoroughly test an application to identify as many flaws as possible to guarantee that a quality product reaches the consumer. Before going on to the workflow and different phases of the defect, it is ...
Read MoreCurve Fitting Models in Software Engineering
Curve fitting is the process of constructing a curve, or mathematical function, that best fits a set of data points, subject to constraints. Curve fitting can include either interpolation, which requires a precise fit to the data, or smoothing, which involves creating a "smooth" function that approximates fits the data.Regression analysis is a similar topic that focuses on statistical inference problems such as how much uncertainty is present in a curve that is fit to data seen with random errors.Fitted curves can be used to help in data visualization, predict function values when no data is provided, and describe the ...
Read MoreFind the column and row names in the R data frame based on condition.
To find the column names and row names in an R data frame based on a condition, we can use row.names and colnames function. The condition for which we want to find the row names and column names can be defined inside these functions as shown in the below Examples.Example 1Following snippet creates a sample data frame −x1
Read MoreBest Web Application Testing Tools
We use web app testing tools to enhance reliability, reduce turnaround time and to increase ROI (return on investment).ZAPTESTThis software automation tool is used by those organizations who use software operations/development. It is also used by those organizations who are looking to automate their back-office operations or software testing process. ZAPTEST is also used to develop a seamless automation framework.FeaturesAlso used for automated functional and performance testingUsed in RPA (Robotic Process Automation)Offers seamless testingUsed in executing cross-platform (parallel) testingAutomated DevOps (mock-ups)API (Application Programming Interface) testingAutomatic documentationTestpadThis is an easy-to-use manual testing tool used for testing web applications. It is easily ...
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