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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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How to Create an Array and Its Types in Python

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Python supports various array types. Here is a list of arrays and how to create examples for your reference. 

What is an array?


A Python array is a class that mimics the array type of other languages and offers efficiency in storage, exchanging that for flexibility.

How to create an array


Here is the syntax to create an array:

data = array('f', [12.8, 5.4, 8.0, 8.0, 9.21, 3.14])


It creates an array of 6 floating point numbers; the type is indicated by the 'f' as the first parameter to the constructor. This concept is unlike the Python norm of types being dynamic and malleable. An array is an array of one kind of thing, and an array can only hold a restricted set of types.


Array types

Types of arrays

Here is a list of arrays:

'b' A C++ char type
'B' A C++ unsigned char type
'i': A C++ int type
'l': A C++ long type
'f': A C++ float type
'd': A C++ double type

What is an array type?

Arrays are class objects and are provided in the built-in module array, which must be imported:

from array import array

An array is a sequence type and has the basic properties and operations that Python provides for all sequence types. Array elements can be assigned to and can be used in expressions, and arrays can be searched and extended like other sequences.

Tips: I have referred some best books and Udemy course. I am giving here for your ready reference. The best Udemy course is Python Bootcamp and the best Python book is Python pocket primer.
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