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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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Unix: How to Write Shell Script Using vi Editor

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Unix Commands
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When you login into UNIX, you are first in the home directory:

$/home:

Then you can issue

 $/home: cd jthomas

Then you come to your own directory:

$/home/jthomas:

How to write your first script:
$/home/jthomas: vi test.sh

Here, you can write your script.
The first line in the script is:

#!/bin/ksh - It denotes which shell you are going to use.

Example:

$vi test.sh

  #!/bin/ksh 
################################################### # 
Written By: Jason Thomas # Purpose: This script was written to show users 
how to develop their first script 
################################################### # Denotes a comment

root

daemon bin sys adm uucp nobody lpd

How to run a script

$ sh test.sh

 Also read: The complete list of UNIX basic commands

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