kopia lustrzana https://github.com/animator/learn-python
Merge pull request #536 from Santhosh-Siddhardha/main
Added Saving Arrays into Files section under NumPy modulepull/551/head
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- [Basic Mathematics](basic_math.md)
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- [Basic Mathematics](basic_math.md)
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- [Operations on Arrays in NumPy](operations-on-arrays.md)
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- [Operations on Arrays in NumPy](operations-on-arrays.md)
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- [Loading Arrays from Files](loading_arrays_from_files.md)
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- [Loading Arrays from Files](loading_arrays_from_files.md)
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- [Saving Numpy Arrays into FIles](saving_numpy_arrays_to_files.md)
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# Saving NumPy Arrays to Files
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- Saving arrays in NumPy is important due to its efficiency in storage and speed, maintaining data integrity and precision, and offering convenience and interoperability.
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- NumPy provides several methods to save arrays efficiently, either in binary or text formats.
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- The primary methods are `save`, `savez`, and `savetxt`.
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### 1. numpy.save():
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The `np.save` function saves a single NumPy array to a binary file with a `.npy` extension. This format is efficient and preserves the array's data type and shape.
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#### Syntax :
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```python
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numpy.save(file, arr, allow_pickle=True, fix_imports=True)
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```
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- **file** : Name of the file.
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- **arr** : Array to be saved.
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- **allow_pickle** : This is an Optional parameter, Allows saving object arrays using Python pickles.(By Default True)
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- **fix_imports** : This is an Optional parameter, Fixes issues for Python 2 to Python 3 compatibility.(By Default True)
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#### Example :
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```python
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import numpy as np
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arr = np.array([1,2,3,4,5])
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np.save("example.npy",arr) #saves arr into example.npy file in binary format
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```
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Inorder to load the array from example.npy
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```python
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arr1 = np.load("example.npy")
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print(arr1)
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```
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**Output** :
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```python
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[1,2,3,4,5]
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```
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### 2. numpy.savez():
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The `np.savez` function saves multiple NumPy arrays into a single file with a `.npz` extension. Each array is stored with a unique name.
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#### Syntax :
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```python
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numpy.savez(file, *args, **kwds)
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```
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- **file** : Name of the file.
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- **args** : Arrays to be saved.( If arrays are unnamed, they are stored with default names like arr_0, arr_1, etc.)
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- **kwds** : Named arrays to be saved.
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#### Example :
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```python
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import numpy as np
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arr1 = np.array([1,2,3,4,5])
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arr2 = np.array(['a','b','c','d'])
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arr3 = np.array([1.2,3.4,5])
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np.savez('example.npz', a1=arr1, a2=arr2, a3 = arr3) #saves arrays in npz format
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```
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Inorder to load the array from example.npz
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```python
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arr = np.load('example.npz')
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print(arr['a1'])
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print(arr['a2'])
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print(arr['a3'])
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```
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**Output** :
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```python
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[1 2 3 4 5]
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['a' 'b' 'c' 'd']
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[1.2 3.4 5. ]
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```
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### 3. np.savetxt()
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The `np.savetxt` function saves a NumPy array to a text file, such as `.txt` or `.csv`. This format is human-readable and can be used for interoperability with other tools.
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#### Syntax :
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```python
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numpy.savetxt(fname, X, delimiter=' ', newline='\n', header='', footer='', encoding=None)
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```
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- **fname** : Name of the file.
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- **X** : Array to be saved.
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- **delimiter** : It is a Optional parameter,This is a character or string that is used to separate columns.(By Default it is " ")
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- **newline** : It is a Optional parameter, Character for seperating lines.(By Default it is "\n")
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- **header** : It is a Optional parameter, String that is written at beginning of the file.
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- **footer** : It is a Optional parameter, String that is written at ending of the file.
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- **encoding** : It is a Optional parameter, Encoding of the output file. (By Default it is None)
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#### Example :
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```python
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import numpy as np
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arr = np.array([1.1,2.2,3,4.4,5])
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np.savetxt("example.txt",arr) #saves the array in example.txt
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```
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Inorder to load the array from example.txt
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```python
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arr1 = np.loadtxt("example.txt")
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print(arr1)
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```
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**Output** :
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```python
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[1.1 2.2 3. 4.4 5. ]
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```
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By using these methods, you can efficiently save and load NumPy arrays in various formats suitable for your needs.
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