Broadcasting and general functions
Broadcasting is a core concept of NumPy that allows performing element-wise operations on scalars or arrays with other arrays of different shapes. Universal functions (ufuncs) are predefined functions that are applied to each element of an array. By combining broadcasts and ufuncs, efficient and concise data manipulation can be achieved.
General function example:
np.multiply(A, B)
np.greater(A, B)
np.sin(x)
Advanced Indexing and Slicing
Advanced Indexes and slicing provide flexible data access beyond standard indexes. Boolean indexing selects elements that meet specific criteria, while fancy indexing and advanced slicing allow elements on multiple axes to be indexed using arrays or lists.
Advanced indexing example:
A[A > 5]
A[np.array([0, 2, 4])]
A[::2, 1::2]
Array aggregation and reduction
Aggregation functions are used to group or summarize data in an array. The reduction function reduces the elements in an array to a single scalar value. Common aggregate functions include:
np.sum()
np.mean()
np.max()
np.min()
Sort and unique values
SortThe algorithm sorts the elements of an array, while the unique value function returns a set of the unique elements in the array. These functions are very useful for data analysis and data cleaning.
Sort example:
np.sort(x)
np.sort(A, axis=1)
Unique value example:
np.unique(A)
np.unique(A, return_counts=True)
Combination of broadcast, advanced indexing and aggregation
Complex data operations can be achieved by combining broadcast, advanced indexing and aggregation. For example, you can sum specific rows or columns in an array, or count elements that meet a specific condition.
example:
np.sum(A, axis=0)
np.mean(A[A > 5])
Performance optimization
By taking advantage of NumPy's vectorization, broadcasting, and efficient underlying implementation, the performance of data operations can be optimized. Other Performance Optimization tips include:
Other advanced features
NumPy also provides other advanced features, such as:
Example
NumPy’s advanced techniques are useful in a variety of applications, including:
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