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Top Questions People Ask About Pandas, NumPy, Matplotlib & Scikit-learn — Answered!

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 Whether you're a beginner or brushing up on your skills, these are the real-world questions Python learners ask most about key libraries in data science. Let’s dive in! 🐍 🐼 Pandas: Data Manipulation Made Easy 1. How do I handle missing data in a DataFrame? df.fillna( 0 ) # Replace NaNs with 0 df.dropna() # Remove rows with NaNs df.isna(). sum () # Count missing values per column 2. How can I merge or join two DataFrames? pd.merge(df1, df2, on= 'id' , how= 'inner' ) # inner, left, right, outer 3. What is the difference between loc[] and iloc[] ? loc[] uses labels (e.g., column names) iloc[] uses integer positions df.loc[ 0 , 'name' ] # label-based df.iloc[ 0 , 1 ] # index-based 4. How do I group data and perform aggregation? df.groupby( 'category' )[ 'sales' ]. sum () 5. How can I convert a column to datetime format? df[ 'date' ] = pd.to_datetime(df[ 'date' ]) ...
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2 Exclusive Ways to Start Kafka Services

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The Kafka services start or stop you can do in two ways. Those are Systemd and Systemctl (sudo user). Below, you will find the commands for these two methods.


2 Ways to start Kafka Services


How to start/stop Kafka service

Here are exclusive ways. With these, you can start or stop Kafka services.  

1. Systemd service

The concept of unit files people who worked on Linux servers have familiarity with it. Also, they know creating the unit file to use by systemd.

To summarize, it initializes and maintains components throughout the system. This means that you can define ZooKeeper and Kafka as unit files, which then will be used by systems.


Commands

The first command starts the service, and the second command stops the service.

... [Service] ...

ExecStart=/opt/kafkainaction/bin/zookeeper-server-start.sh
ExecStop= /opt/kafkainaction/bin/zookeeper-server-stop.sh


2. Systemctl by Sudo (root) user

The root user can start or stop the Kafka services. This is more like front-end processing. This way of executing is called systemctl.

Commands

The first command starts the Zookeeper and the second one starts Kafka.

$sudo systemctl start zookeeper
$sudo systemctl start kafka

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