Amazon Web Services

A network ACL is a network security for your Amazon VPC that acts as a firewall for controlling traffic in and out of one or more subnets. Security Groups is security placed at server level which is first level of defence

When You require a fast and flexible NoSQL database with a flexible data model and reliable performance then DynamoDB is the service from AWS

AMI can be elaborated as Amazon Machine Image, basically, a template consisting software configuration part. For example an OS, applications, application server. If you start an instance, a duplicate of the AMI in a row as an unspoken attendant in the cloud.

Starting and stopping of an instance: If an instance gets stopped or ended, the instance functions a usual power cut and then change over to a clogged position. You can establish the case afterward since all the EBS volumes of Amazon remain attached. If an instance is in stopping state, then you will not get charged for additional instance. Finishing the instance: If an instance gets terminated it tends to perform a typical blackout, so the EBS volumes which are attached will get removed except the volume’s deleteOnTermination characteristic is set to zero. In such cases, the instance will get removed and cannot set it up afterward.

Yes, it is possible. Just stop the server and then change its instance type and again start server.

Auto- scaling is one of the remarkable features of AWS where it permits you to arrange and robotically stipulation and spin up fresh examples without the requirement for your involvement. This can be achieved by setting brinks and metrics to watch. If those entrances are overcome, a fresh example of your selection will be configured, spun up and copied into the weight planner collection.

The aptitude of any scheme to enhance the tasks on hand on its present hardware resources to grip inconsistency in command is known as scalability. The capability of a scheme to augment the tasks on hand on its present and supplementary hardware property is recognized as flexibility, hence enabling the industry to convene command devoid of putting in the infrastructure at all. AWS has several configuration management solutions for AWS scalability, flexibility, availability and management.

PaaS : Platform as a Service
IaaS : Infrastructure as a Service
SaaS : Software as a Service

One thing must be ensured that no one should seize the information in the cloud while data is moving from point one to another and also there should not be any leakage with the security key from several storerooms in the cloud. Segregation of information from additional companies’ information and then encrypting it by means of approved methods is one of the options.

An Elastic Load Balancer ensures that the incoming traffic is distributed optimally across various AWS instances. A buffer will synchronize different components and makes the arrangement additional elastic to a burst of load or traffic. The components are prone to work in an unstable way of receiving and processing the requests. The buffer creates the equilibrium linking various apparatus and crafts them effort at the identical rate to supply more rapid services.


No, you do not need any Jquery for AngularJS. It’s free of Jquery.

The link function deals with linking scope to the DOM.

Compile traverses the DOM and collects all of the directives and deals with transforming the template DOM. The result is a linking function.

Ajax is used to communicate every time with a server without causing the browser to load new content and, in doing so, dump your AngularJS application. That said, if you are consuming data from a RESTful API, then you should use the $resource service. I will describe REST and $resource in the next article, but the short version is that $resource provides a higher-level API that is built on the services I describe in this article and makes it easier to perform common data operations.

AngularJS module is a container of all angular components like controller, services, directive, filter, config etc. Using module we can decide how the AngularJS application should be bootstrapped.

Currency filter includes the “$” Dollar Symbol as the default. Given below is the html template format of Currency Filter. {{ currency_expression | currency : symbol : fractionSize}}

Data binding is a very powerful feature of the software development technologies which acts as the connection bridge between view and business logic model of the application. Data binding in AngularJS is the automatic synchronization between the model and view.

ng- disabled directive is used to enable or disable HTML elements.

AngularJS is written using JavaScript.

No, you do not need any Jquery for AngularJS. It’s free of Jquery.

Big Data Hadoop

The three configuration files are 1)core-site.xml 2) mapred-site.xml 3) hdfs-site.xml

Hadoop has a unique way of indexing. Once the data is stored as per the block size, the HDFS will keep on storing the last part of the data which say where the next part of the data will be.

Yes, it is possible to search for files using wildcards

Namenode is the single point of failure in HDFS so when Namenode is down your cluster will set off.

To store binary key/value pairs, sequence file is used. Unlike regular compressed file, sequence file support splitting even when the data inside the file is compressed.

No, it is not possible to change the number of mappers to be created. The number of mappers is determined by the number of input splits.

You write a custom partitioner for a Hadoop job, you follow the following path • Create a new class that extends Partitioner Class • Override method getPartition • In the wrapper that runs the MapReduce • Add the custom partitioner to the job by using method set Partitioner Class or – add the custom partitioner to the job as a config file

It splits input files into chunks and assign each split to a mapper for processing.

The most common input formats defined in Hadoop are;

  • TextInputFormat
  • KeyValueInputFormat
  • SequenceFileInputFormat

The data storage component used by Hadoop is HBase.


<header > : It is mainly used to store and define the starting information about a web page section.
<article>: It is used to define a set of information which can be logically independent and also can be described with respect to the concerned web page business logic.
<section>: It mainly consists of a set of instructions that defines the basic structure and content of the page
<footer>: This is used to hold a set of information that is getting displayed at the last portion of a webpage

session Storage stores data as per the different web sessions availability and thus if any window or tab is permanently closed then any data or records which are stored through sessionStorage will be deleted. But in the case of local storage, the storing procedure is permanent and hence all the records will remain stored on the user’s device until the user instructs the browser to delete it.

The new input type are:Time,Date,Datetime,Datetime-local,Week,Month,Email,Color,Number,Range,Search,Telephone,URL

An input tag can take some attributes based on the requirement. ie < input type=”text” >creates a textbox that takes text/number/special characters into it. The attribute type can take more values, these are:
Datetime: Gives a datetime accepted textbox.
Placeholder: Places an editable text in the textbox.
Number: Takes only numbers and no text and special characters.
Tel: Takes inputs like a telephone number.
Email: Takes text with email format.

Two storage types of HTML5 are:
Session Storage: It stores data of current session only. It means that the data stored in session storage clear automatically when the browser is closed.
Local Storage: Local storage is another type of HTML5 Web Storage. In local storage, data is not deleted automatically when the current browser window is closed.

The canvas element helps to build charts, graphs, bypass Photoshop to create 2D images and place them directly into HTML5 code

This tag represents a piece of self-contained flow content. It is mostly used as a single unit as a reference the main flow of the document

The available API’s in HTML are:DOM Level 1,DOM Level 2 Core, DOM Level 2 HTML,DOM Level 3

The form attribute novalidate is a Boolean type which takes true/false values. If disabled or made false, the form data is not validated when submitted.

HTML5 has two types of providing graphics, SVG and Canvas. SVG is helpful when using devices like tablets, iPads etc. Whereas, Canvas is an area in the document or HTML page where graphics can be drawn


An alert box displays only one button which is the OK button. But a Confirmation box displays two buttons namely OK and cancel.

All variables in the JavaScript are object data types.

Void(0) is used to prevent the page from refreshing and parameter “zero” is passed while calling. Void(0) is used to call another method without refreshing the page.

1)  Alert 2)   Confirm 3)   Prompt

Undefined value means the • Variable used in the code doesn’t exist • Variable is not assigned to any value • Property doesn’t exist

The delete keyword is used to delete the property as well as its value. Example var student= {age:20, batch:”ABC”}; delete student.age;

The NULL value is used to represent no value or no object. It implies no object or null string, no valid boolean value, no number and no array object.

In order to detect the operating system on the client machine, the navigator.platform string (property) should be used.

“==” checks only for equality in value whereas “===” is a stricter equality test and returns false if either the value or the type of the two variables are different.

The parseInt() function is used to convert numbers between different bases. parseInt() takes the string to be converted as its first parameter, and the second parameter is the base of the given string. In order to convert 4F (of base 16) to integer, the code used will be – parseInt (“4F”, 16);


Python language is an interpreted language. Python program runs directly from the source code. It converts the source code that is written by the programmer into an intermediate language, which is again translated into machine language that has to be executed.

NumPy is a Python package for scientific computing which can deal with large data sizes. It includes a powerful N-dimensional array object and a set of advanced functions.

Everything in Python is an object and all variables hold references to the objects. The references values are according to the functions; as a result you cannot change the value of the references. However, you can change the objects if it is mutable.

The difference between list and tuple is that list is mutable while tuple is not. Tuple can be hashed for e.g as a key for dictionaries.

A Python decorator is a specific change that we make in Python syntax to alter functions easily.

The way of implementing iterators are known as generators. It is a normal function except that it yields expression in the function.

Flask supports database powered application (RDBS). Such system requires creating a schema, which requires piping the shema.sql file into a sqlite3 command. So you need to install sqlite3 command in order to create or initiate the database in Flask. Flask allows to request database in three ways
before_request() They are called before a request and pass no arguments
after_request() : They are called after a request and pass the response that will be sent to the client
teardown_request(): They are called in situation when exception is raised, and response are not guaranteed. They are called after the response been constructed. They are not allowed to modify the request, and their values are ignored.

A string in Python is a sequence of alpha-numeric characters. They are immutable objects. It means that they don’t allow modification once they get assigned a value. Python provides several methods, such as join(), replace(), or split() to alter strings. But none of these change the original object.

Python decorator is a relative change that you do in Python syntax to adjust the functions quickly.

In order to convert a number into a string, use the inbuilt function str(). If you want a octal or hexadecimal representation, use the inbuilt function oct() or hex().

R Programming

As a data manipulation and visualization tool, R can most definitely be used for predictive analytics. Using the same sort of decision tree we developed earlier, one could predict how many shootings might occur in 2019 in Boston. R as a whole provides numerous tools and packages for predictive modelling, so it’s the right tool for a data scientist.

R turns otherwise hours of graphically intensive jobs into minutes and keystrokes. In reality, you probably wouldn’t encounter the language of R outside the realm of data science or an adjacent field. It’s great for linear modeling, nonlinear modeling, time-series analysis, plotting, clustering, and so much more. Simply put, R is designed for data manipulation and visualization, so it’s natural that it would be used for data science.

Simply use the read.csv() function. yourRDateHere <- read.csv(“Data.csv”, header = TRUE)

A factor variable is a form of categorical variable that accepts either numeric or character string values. The most salient reason to use a factor variable is that it can be used in statistical modelling with great accuracy. Another reason is that they are more memory efficient. Simply use the factor() function to create a factor variable.

By default, mode() gets or sets the storage mode of an object. It’s default usage is equivalent to storage.mode().

We use the with() function to write simpler code by applying an expression to a data set. Its syntax looks like this: with(randomDataSet, expression.test(sample))

To save data in R, there are many ways, but the easiest way of doing this is Go to Data > Active Data Set > Export Active Data Set and a dialogue box will appear, when you click ok the dialogue box let you save your data in the usual way.

In R, subset() functions help you to select variables and observations while through sample() function you can choose a random sample of size n from a dataset.

rbind function can be used to join two data frames (datasets). The two data frames must have the same variables, but they do not have to be in the same order.

This is a variant of the “advantages of R” question. Reasons to use R include its open-source nature and the fact that it’s a versatile tool for statistical plotting, analysis, and portrayal. Don’t be afraid to give some personal reasons as well. Maybe you simply love the assignment operator in R or feel that it’s more elegant than other languages—but always remember to explicate. You should be answering follow-up questions before they’re even asked.


You need to create two sets. The first one containing the top 5 records while the other one with bottom 5. Then join these two sets by displaying a total set of 10 records.

Shelves are named areas to the left and to the top of the view. Views are built using fields by placing them onto shelves. Sets, on the other hand, are the custom fields used to define a data subset primarily based on conditions. A set can be based upon a specific computed condition. For example, a set contains customers with sales more than a particular threshold. These sets get updated as and when your data changes.

A maximum of 32 tables can be joined.

It is a distinct and a powerful tool to control the output display. It fragments the view into the line of pages thereby giving a different view on every page. This minimizes the scrolling and makes it more user-friendly. The pages can be flipped through specific controls and compared at the common axle.

The components are: 1.Horizontal 2.Vertical 3.Text 4.Image Extract 5.Web[URL ACTION]

Data extracts are the first subdivisions or copies of actual data from original data sources. The workbook using data extracts instead of living connections is faster. After the extraction of data users can publish their workbook. Scheduled refresh is the scheduled task set used to refresh the data extract. This saves from the effort of republishing the workbook every time the data gets updated.

It makes the filtering process smooth and straightforward. It is used to establish a filtering hierarchy where all the present filters are used to refer to context filters while other filters process the data which has been already passed by the context filter. More than one context filter creation is used to improve performance as extra filters are not created and thus the query execution time is also maintained. This can be created by dragging the field into filters tab and right click on the field and select “Add to context”. Limitations of context filter: By default time is taken to place a filter in context. A temporary file is created as soon as the filter is set to context one for that context filter. The table will reload every time and it will contain the values not filtered by either context filter or by custom SQL filter.

They both are the ways used to develop a scatterplot in order to measure and compare data values. Aggregation, as the name suggests, is the calculated form of a specific set of values which return a single numeral value. For instance, a set of values such as 1, 3, 5, 7 will return the value The default aggregation like sum, median, average, count, etc. are not user-defined. Disaggregating data is used to refer to viewing every data source row and analyzing data both dependently as well as independently.

Measures are the numeric quantities or measurable metrics of data analyzed easily by the dimension table. They are stored in the table containing foreign keys which refers uniquely to the associated dimension tables. The data stored in the table is in atomic form thereby allowing more number of records to be inserted at a particular time. A sales table, for instance, can contain product key, customer key, items sold, promotion key, etc. details which are referring to a particular event. Dimensions, on the other hand, are descriptive attribute values used for multiple dimensions of an attribute which defines different characteristics. A dimension table can consist values like product name, type, product size, description, color, etc.

Tableau is an interactive data visualization product majorly focused on providing business intelligence. It is used to connect to the data, visualize it and create interactive dashboards for further analysis. Below is the list of different Tableau products:
Tableau Desktop: A self-service data visualization and business analytics tool which is easily accessible. This is used to translate data images into optimized queries. The data warehouse can be directly used to connect with the live data up to data analysis completion. Query execution can be performed without writing a single line of code. All the data from various sources can be imported into Tableau’s data engine and integrated by combining all the views in the form of an interactive dashboard.
Tableau Server: This enterprise level Tableau software can be used to publish Tableau desktop based dashboards and share them using web-based Tableau server throughout the organization. It is used to leverage fast database by making use of live connections.
Tableau online: Tableau server’s hosted version is used to make business intelligence easier and faster than before. Tableau dashboards can be shared with colleagues by using tableau desktop.
Tableau Reader: Free desktop application which enables you to view visualizations primarily built on Tableau Desktop. Filtering and drilling down of data is possible but editing or any kind of interactions is not possible in this case.
Tableau Public: As the name suggests, this is the free version of Tableau software which can be used to make visualizations once the workbooks are saved on the Tableau server which can then be viewed by anyone.

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