Featured Post

How to Check Column Nulls and Replace: Pandas

-
Image
Here is a post that shows how to count Nulls and replace them with the value you want in the Pandas Dataframe. We have explained the process in two steps - Counting and Replacing the Null values. Count null values (column-wise) in Pandas ## count null values column-wise null_counts = df.isnull(). sum() print(null_counts) ``` Output: ``` Column1    1 Column2    1 Column3    5 dtype: int64 ``` In the above code, we first create a sample Pandas DataFrame `df` with some null values. Then, we use the `isnull()` function to create a DataFrame of the same shape as `df`, where each element is a boolean value indicating whether that element is null or not. Finally, we use the `sum()` function to count the number of null values in each column of the resulting DataFrame. The output shows the count of null values column-wise. to count null values column-wise: ``` df.isnull().sum() ``` ##Code snippet to count null values row-wise: ``` df.isnull().sum(axis=1) ``` In the above code, `df` is the Panda
Post a Comment

The awesome points to learn from DB2 NoSQL GraphStore

-
The awesome points to learn from db2 graphstore
 #db2 graphstore:
One best example, prior to understanding the RDF format for Graph data model- If the graph data model is the model the semantic web uses to store data, RDF is the format in which it is written. 


Summary of DB2 Graph Store:
  • DB2-RDF support is officially called "NoSQL Graph Support".  
  • The API extends the Jena API (Graph layer).  Developers familiar with Jena TDB will have the Model layer capabilities they are accustomed to.
  • Although the DB2-RDF functionality is being released with DB2 LUW 10.1, it is also compatible with DB2 9.7.
  • Full supports for SPARQL 1.0 and a subset of SPARQL 1.1.  Full SPARQL 1.1 support (which is till a W3C working draft) will be forthcoming.
  • While RDBMS implementations of RDF graphs have typically been non-performant, that is not the case here*.  Some very impressive and innovative work has been put into optimization capabilities.  Out-of-the box performance is comparable with native triple stores, and read/write performance in the optimized schema has been seen to surpass these speeds.
Related: Presentation on DB2 NoSQL Graph Store

What is RDF data model(ref:wiki)

The RDF data model is similar to classical conceptual modeling approaches such as entity–relationship or class diagrams, as it is based upon the idea of making statements about resources (in particular web resources) in the form of subject–predicate–object expressions.  

 These expressions are known as triples in RDF terminology. The subject denotes the resource, and the predicate denotes traits or aspects of the resource and expresses a relationship between the subject and the object. For example, one way to represent the notion "The sky has the color blue" in RDF is as the triple: a subject denoting "the sky", a predicate denoting "has", and an object denoting "the color blue". Therefore, RDF swaps object for subject that would be used in the classical notation of an entity–attribute–value model within object-oriented design; Entity (sky), attribute (color) and value (blue). RDF is an abstract model with several serialization formats (i.e., file formats), and so the particular way in which a resource or triple is encoded varies from format to format. 

 This mechanism for describing resources is a major component in the W3C's Semantic Web activity: an evolutionary stage of the World Wide Web in which automated software can store, exchange, and use machine-readable information distributed throughout the Web, in turn enabling users to deal with the information with greater efficiency and certainty. 
RDF's simple data model and ability to model disparate, abstract concepts has also led to its increasing use in knowledge management applications unrelated to Semantic Web activity. 
A collection of RDF statements intrinsically represents a labeled, directed multi-graph. As such, an RDF-based data model is more naturally suited to certain kinds of knowledge representation than the relational model and other ontological models. However, in practice, RDF data is often persisted in relational database or native representations also called Triplestores, or Quad stores if context (i.e. the named graph) is also persisted for each RDF triple.[3] ShEX, or Shape Expressions,[4] is a language for expressing constraints on RDF graphs. It includes the cardinality constraints from OSLC Resource Shapes and Dublin Core Description Set Profiles as well as logical connectives for disjunction and polymorphism. As RDFS and OWL demonstrate, one can build additional ontology languages upon RDF.

Related:

Comments

Post a Comment

Thanks for your message. We will get back you.

Popular posts from this blog

Explained Ideal Structure of Python Class

-
Image
When you are designing a class, you need to ensure that the classification of its critical parts is outlined at the beginning. The clearer the initial design, the more performant and scalable the class is. Some of the components in the order in which they should be defined in the class are mentioned as follows. Ideal structure of a class Class variables Constants or default variables are usually defined at the top of the class. For someone who is reading the code, it comes as an easy-to-view consolidated list, and for the interpreter it ensures that all such variables are processed before diving into the main logic of the class, including any other Instance method or constructor. The __init__ method The __init__ method provides information about inputs needed and how to instantiate the class. It is also the constructor of the class, which the very first method called while initializing the class . Special Python methods These methods change the functionality of the class or provide add
Read more

How to Check Kafka Available Brokers

-
Image
Here's the command to check the list of brokers present in a Kafka Cluster. You can say the Broker is the heart of the Kafka cluster. In simple terms, it works as a process. The main function is to receive messages from publishers and gives permission to access messages by consumers. How to Check Available Brokers in Kafka Here is the command: linux$  ./zookeeper-shell.sh zookeeper-IPaddress:2181 | "ls /brokers/ids" Just use the above command to get the number of brokers present in your host (Kafka Cluster). What is Default Broker-id in Kafka  The default broker id is -1 . When you create a new broker, it adds to -1. Then, it gives a new broker id. The broker ids will be generated from  reserved.broker.max.id + 1. Types of broker ids. Use assigned Zookeeper generated broker id. According to Wiki: Kafka runs on a cluster of one or more servers (called brokers), and the partitions of all topics are distributed across the cluster nodes.  Additionally, partitions are replicat
Read more

6 Python file Methods Real Usage

-
Image
Files always have data in them. For different purposes, you need methods to deal with them. These six file methods of use in this case. Related:  5 top file modes in python. Python file methods Below are the top six file methods in python: Tell() Seek() Flush() Fileno() truncate() isatty() 1. tell() The usage of tell method is it  returns the cursor-position of the file-pointer from the beginning of the file. It tells the current cursor position. The position starts from zero, which is same as of an index. Syntax:  fileobject.tell() 2. seek() The usage of seek  method is cursor position, from one position to the specified position from the beginning of the file, it moves. Here, the cursor will be sought to a particular location. Syntax:  fileobject.seek(position) 3. flush() The usage of flush  method is clean out the internal buffer. Before writing the text in the file, it is best practice to clear out that the internal buffer can be cleared. Syntax:  fileobject.flush() 4. fileno() The
Read more