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NumPy is a Python library for scientific computing that contains support for some fundamental data structures used by scikit-learn, such as multi-dimensional arrays. Example import: `import numpy as np`

NumPy

Developers need to know what works and how to use it. This site uses less math and more tutorials with working code.
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NumPy Documentation

Typically, data that's input to scikit-learn will be in the form of a NumPy array.

NumPy vs. Scikit-learn

What does the following code do?

Consider the following code: what will be c?

Consider the two following random arrays "a" and "b" below: what will be the shape of "c"?

Because the Numpy array is densely packed in memory due to its homogeneous type, Numpy gets around 30 times faster than Python.

Make big difference when handling big data.

Numpy Speed


In NumPy, there are two objects that are crucial to understanding how this library works. Those are:

1. N-dimensional array object (ndarray)

2. Universal function object (ufunc)

However, keep in mind that there are other objects that are built upon these that can be incorporated into whatever you're doing.

Fundamental Objects in NumPy

Within the NumPy library, there are several types of mathematical functions built-in. These functions are typically used across elements of a NumPy array.

Types of Mathematical Functions:
- Trigonometric
- Rounding
- Exponents and Logarithms
- Arithmetic
- Other Special Functions

Mathematical Functions in NumPy

While Python natively provides built-in data types such as booleans, floats, and integers, NumPy offers additional specialized data types. These are often referred to by single-character codes:
- `i`: integer
- `b`: boolean
- `u`: unsigned integer
- `f`: float
- `c`: complex float
- `m`: timedelta
- `M`: datetime
- `O`: object
- `S`: string
- `U`: unicode string
- `V`: void (fixed chunk of memory for other types)

Data Types in NumPy

Recall that "np.dot(a,b)" performs a matrix multiplication on a and b, whereas "a*b" performs an element-wise multiplication. Consider the two following random arrays "a" and "b": what is the shape of c?

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