Definition
NumPy என்பது Python-ல் numerical data-ஐ fast-ஆக process செய்ய பயன்படும் powerful library. NumPy full form: Nu……
NumPy
NumPy என்பது Python-ல் numerical data-ஐ fast-ஆக process செய்ய பயன்படும் powerful library. NumPy full form: Numerical Python NumPy-ன் முக்கிய purpose: Arrays, matrices, mathematical operations, statistical calculations, scientific computing…
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145 programs 19 MCQs v2
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Simple Explanation
Normal Python list: numbers = [10, 20, 30, 40] இது multiple values store செய்யும். ஆனால் large numerical data……
Flow
Install NumPy ↓ Import NumPy ↓ Create NumPy Ar……
Program
Example
Syntax
NumPy import
Syntax
Array creation
Program
Example
Important
Python list output: [10, 20, 30] Num……
Why NumPy?
NumPy use செய்வதற்கு முக்கிய காரணங்கள்: Fast numerical calculations Less code Multidimensional arrays Mat……
Comparison
Python List vs NumPy Array
Important
Very Important Difference Pyt……
List repeat ஆகிறது. NumPy:…
ஒவ்வொரு element-மும் multiply……
Installing NumPy
Command Prompt / Terminal: pip ins……
Important
NumPy Python Standard Library-ன் built-in module அல்ல. ……
Importing NumPy
Program
Normal
Use: numpy.array([1, 2, 3]) C……
Then: np.array([1, 2, 3])…
Memory Trick
NumPy → np Pandas → pd Matplo……
NumPy Array
Definition
NumPy-ன் main data structure: ndarray Full form: N-dimensional Array nd……
Simple Explanation
1D array: [10 20 30] 2D array: [[……
TRB Point
The fundamental array object ……
One-Dimensional Array - 1D
A one-dimensional array is li……
Two-Dimensional Array - 2D
A 2D array contains rows and ……
Rows: [10 20] [30 40] Columns……
Three-Dimensional Array - 3D
Conceptually: 2 blocks ↓ Each……
Important
Dimensions: 1D → One axis 2D ……
ndim
ndim tells number of dimensio……
Program
2D
Memory Trick
ndim = Number of Dimensions…
shape
Definition
shape tells the size of each dime……
Definition
Meaning
3 elements. 2D: a = np.array(……
Definition
Meaning
2 rows 3 columns…
Memory Trick
shape = Rows and Columns Stru……
size
size gives total number of el……
Because: 2 rows × 3 columns =……
dtype
Definition
dtype tells the data type of NumPy array el……
Output
Possible output
or depending on platform: int……
Output
Possible output
Important
Exact integer dtype may vary based on pl……
Comparison
ndim vs shape vs size vs dtype
Memory Trick
N S S D N → ndim → Number of dimensions S……
Indexing in NumPy
Definition
Indexing means accessing an individua……
Explanation
Array: [10 20 30 40] Indexes:……
Negative Indexing
-1 means last element.…
2D Indexing
Definition
Meaning
a[row, column] Here: Row 0 Co……
Memory Trick
2D: array[row, column]…
Slicing
Definition
Slicing means accessing a rang……
Important
start included. stop excluded.…
Why? Start index 1 included. ……
Slice with Step
Explanation
Syntax
array[start:stop:step]…
Program
Example
Change Array Value
NumPy arrays are mutable.…
Important
NumPy array is mutable. Exist……
Array Arithmetic
This is one of the most impor……
5 ஒவ்வொரு element-க்கும் add ……
Important
This is called: Vectorized oper……
Array-to-Array Operations
Calculation: 10 + 1 = 11 20 +……
Important
This is element-wise multipli……
Common Mistake
Students may think: a * b does matrix multiplication. Not necessarily. For normal NumPy ar……
Mathematical Functions
NumPy provides many mathemati……
Aggregate Functions
Aggregate means summarizing m……
np.arange()
Definition
np.arange() creates evenly sp……
Explanation
Syntax
np.arange(start, stop, step)…
Stop value 6 excluded.…
Comparison
Python range() vs NumPy arange()
np.linspace()
Definition
linspace() creates a specified nu……
Explanation
Syntax
np.linspace(start, stop, numb……
Important
linspace()-ல் stop value norm……
Comparison
arange() vs linspace()
Memory Trick
arange → Give me the gap / st……
np.zeros()
Creates array filled with zer……
Program
2D
np.ones()
np.full()
Create array filled with a sp……
Program
2D
Identity Matrix - np.eye()
Definition
Identity matrix: Main diagona……
Reshaping Arrays
Definition
Reshaping means changing arra……
Program
Example
Common Mistake
Wrong: a.reshape(4, 2) 6 elem……
Important
Reshape condition: Original n……
Memory Trick
Reshape: Total elements must ……
Flatten
Convert multidimensional arra……
Transpose
Rows become columns and colum……
Flow
Original: 1 2 3 4 5 6 Transpo……
Concatenation
Join arrays.…
Boolean Filtering
This is a very important NumP……
Explanation
Condition: a > 25 produces conceptually: Fal……
NumPy Comparison
Important
NumPy comparison works elemen……
Copy vs View
This is an important advanced……
Original remains unchanged.…
Because view shares underlyin……
Sorting
Searching
Program
Example using where()
Output
Possible output
Definition
Meaning
20 appears at indexes: 1 and 3…
Random Numbers in NumPy
Modern NumPy commonly uses ran……
Program
Example
Output
Possible output
Definition
Meaning
5 random integers.…
Important
Because values are random, ou……
Matrix Addition
Matrix Element-wise Multiplication
Calculation: 1×5 2×6 3×7 4×8…
Matrix Multiplication
Use: a @ b…
Program
Example
Remember
- → Element-wise multiplicati……
Remember
@ → Matrix multiplication Ver……
Broadcasting
Definition
Broadcasting என்பது different but compatible shapes கொண்ட arrays-க்கு N……
Here scalar 5 behaves as if a……
Simple Explanation
Think: [10 20 30] + [ 5 5 5] = [15 25 35] NumPy ……
TRB Point
Broadcasting allows NumPy to perfor……
Data Type Conversion
Use: astype()…
Program
Example
Important
This truncates decimal parts ……
Explicit dtype
NumPy String and Mixed Values
NumPy usually tries to use a ……
Program
Example
Explanation
Likely output: [10. 20.5] float64 Integer may be ……
Important
NumPy arrays generally work best……
Common Mistake
Error 1
Forgetting Import Wrong: a = np.array([1, 2, 3]) w……
Common Mistake
Error 2
Writing numpy after aliasing to np If: import numpy a……
Common Mistake
Error 3
List multiplication and NumPy m……
Output
Result
NumPy: np.array([1, 2]) * 2…
Output
Result
Common Mistake
Error 4
* means Matrix Multiplication……
Common Mistake
- → Element-wise…
Common Mistake
@ → Matrix multiplication…
Common Mistake
Error 5
Wrong reshape a = np.array([1, 2……
Common Mistake
Error 6
Stop value in slicing a[1:4] Inde……
Common Mistake
Error 7
arange and linspace same என்று நினைப……
Memory Trick
NumPy Master Memory A D S S I M R A → Array D → Dimension S → Shape S → Size I → Indexing M → Mathemat……
TRB Point
TRB Point 1
NumPy stands for: Numerical P……
TRB Point
TRB Point 2
Common alias: import numpy as……
TRB Point
TRB Point 3
Main NumPy array object: ndar……
TRB Point
TRB Point 4
ndim gives number of dimensio……
TRB Point
TRB Point 5
shape gives dimension sizes.…
TRB Point
TRB Point 6
size gives total number of el……
TRB Point
TRB Point 7
dtype gives element data type.…
TRB Point
TRB Point 8
NumPy indexing starts at 0.…
TRB Point
TRB Point 9
NumPy supports negative index……
TRB Point
TRB Point 10
Lists and NumPy arrays behave……
TRB Point
TRB Point 11
NumPy supports element-wise o……
TRB Point
TRB Point 12
np.arange() creates values ba……
TRB Point
TRB Point 13
np.linspace() creates evenly ……
TRB Point
TRB Point 14
np.zeros() creates zero-fille……
TRB Point
TRB Point 15
np.ones() creates one-filled ……
TRB Point
TRB Point 16
np.eye() creates identity mat……
TRB Point
TRB Point 17
reshape() changes array shape……
TRB Point
TRB Point 18
flatten() converts multidimen……
TRB Point
TRB Point 19
.T gives transpose.…
TRB Point
TRB Point 20
- performs element-wise multi……
TRB Point
TRB Point 21
@ performs matrix multiplicat……
TRB Point
TRB Point 22
Boolean indexing can filter v……
TRB Point
TRB Point 23
copy() creates an independent……
TRB Point
TRB Point 24
view() usually shares underly……
TRB Point
TRB Point 25
Broadcasting allows operation……
Interview Point
Question 1
What is NumPy? Answer NumPy is a Python library for numerical and scie……
Interview Point
Question 2
What is ndarray? Answer ndarray stands for N-dimensional ar……
Interview Point
Question 3
Why is NumPy faster than normal Python lists for numerical operations? Answer NumPy arrays s……
Interview Point
Question 4
What is the difference between shape and size? Answer shape desc……
Interview Point
Question 5
What is the difference between arange() and linspace()? Answer arange() generally……
Interview Point
Question 6
What is broadcasting? Answer Broadcasting is NumPy's mechanism……
Interview Point
Question 7
What is the difference betwee……
Interview Point
- performs element-wise multi……
Interview Point
Question 8
What is the difference between copy and view? Answer A copy……
MCQ
NumPy stands for:…
MCQ
Which is the common NumPy ali……
MCQ
Which creates a NumPy array?…
MCQ
What is the output? import nu……
MCQ
Which property gives number o……
MCQ
What does shape return for a ……
MCQ
What does size return for a 2……
MCQ
What is the output? a = np.ar……
MCQ
Which function creates an arr……
MCQ
Which function creates evenly……
MCQ
What is the output? np.arange……
MCQ
What is the output? a = np.ar……
MCQ
Which operator performs eleme……
MCQ
Which operator performs matri……
MCQ
Which method changes the arra……
MCQ
Which converts a multidimensi……
MCQ
What does .T represent?…
MCQ 18
Which is used for Boolean filtering? A. ……
MCQ
Which property tells array el……
MCQ
NumPy is mainly useful for:…
Practice
Practice 1
Create this NumPy array: 10 20 30 40 50……
Practice
Practice 2
Print the third element. prin……
Practice
Practice 3
Print the last element using ……
Practice
Practice 4
Create: 0 2 4 6 8 using NumPy……
Practice
Practice 5
Create 5 evenly spaced values……
Practice
Practice 6
Create a 2 × 3 zeros array. a……
Practice
Practice 7
Create a 3 × 3 identity matri……
Practice
Practice 8
Reshape: [1 2 3 4 5 6] into 2 × 3. ……
Practice
Practice 9
Find: a = np.array([10, 20, 3……
Practice
Practice 10
Filter values greater than 50: a = n……
Practice
Practice 11
Find mean: a = np.array([10, ……
Practice
Practice 12
Find maximum: print(np.max(a))…
Practice
Practice 13
Transpose: a = np.array([ [1,……
Practice
Practice 14
Explain difference between: a……
Practice
- → Element-wise multiplicati……
Practice
@ → Matrix multiplication…
Practice
Practice 15
Find all properties: a = np.array([ [10, 20, 30], [40, 50, 60] ]) Try: print(a.……
Summary
NumPy means Numerical Python. NumPy is used for numerical and scientific computing. Common import is import n……
Summary
- means element-wise multipli……
Summary
@ means matrix multiplication. Broadcasting allows compatible-shape operations. copy() creates independe……
Quick Revision
NumPy → Numerical Python Alias → np Main object → ndarray Create array → np.array() Dimensions → ndim Structu……
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