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How to Check Column Nulls and Replace: Pandas

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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
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Oozie - Concepts And Architecture

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Oozie is a workflow/coordination system that you can use to manage Apache Hadoop jobs. It is one of the main components of Oozie is the Oozie server — a web application that runs in a Java servlet container (the standard Oozie distribution is using Tomcat).

Oozie is a workflow management-server that works on the Oozie server.

Role of Oozie in Workflow Management in Hadoop Jobs

  1. This server supports reading and executing Workflows, Coordinators, Bundles, and SLA definitions. It implements a set of remote Web Services APIs that can be invoked from Oozie client components and third-party applications.
  2. Add a note where the execution of the server leverages a customizable database.
  3. This database contains Workflow, Coordinator, Bundle, and SLA definitions, as well as execution states and process variables.
  4. The list of currently supported databases includes MySQL, Oracle, and Apache Derby. The Oozie shared library component is located in the Oozie HOME directory and contains code used by the Oozie execution.

Oozie Architecture

oozie architecture


How to work with Oozie in Hadoop Framework

Oozie provides a command-line interface (CLI) that is based on a client component, which is a thin Java wrapper around Oozie Web Services APIs.

These APIs can also be used from third-party applications that have sufficient permissions.
A single Oozie server implements all four functional Oozie components:
  • Oozie Workflow 
  • Oozie Coordinator 
  • Oozie Bundle 
  • Oozie SLA 
  • Oozie server is described in this chapter, starting with what Oozie Workflow is and how you can use it.

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