**Prerequisites:** numpy.savetxt(), numpy.loadtxt()

**Numpy.savetxt()** is a method in python in numpy library to save an 1D and 2D array to a file.

Syntax:numpy.savetxt(fname, X, fmt=’%.18e’, delimiter=’ ‘, newline=’\n’, header=”, footer=”, comments=’# ‘, encoding=None)

**numpy.loadtxt()** is a method in python in numpy library to load data from a text file for faster reading.

Syntax:numpy.loadtxt(fname, dtype=’float’, comments=’#’, delimiter=None, converters=None, skiprows=0, usecols=None, unpack=False, ndmin=0)

**Saving and loading 3D arrays**

As discussed earlier we can only use 1D or 2D array in numpy.savetxt(), and if we use an array of more dimensions it will throw a **ValueError –** Expected 1D or 2D array, got 3D array instead. Therefore, we need to find a way to save and retrieve, at least for 3D arrays, here’s how you can do this by using some Python tricks.

**Step 1:**reshape the 3D array to 2D array.**Step 2:**Insert this array to the file**Step 3:**Load data from the file to display**Step 4:**convert back to the original shaped array

**Example:**

## Python3

`import` `numpy as gfg` ` ` ` ` `arr ` `=` `gfg.random.rand(` `5` `, ` `4` `, ` `3` `)` ` ` `# reshaping the array from 3D` `# matrice to 2D matrice.` `arr_reshaped ` `=` `arr.reshape(arr.shape[` `0` `], ` `-` `1` `)` ` ` `# saving reshaped array to file.` `gfg.savetxt(` `"geekfile.txt"` `, arr_reshaped)` ` ` `# retrieving data from file.` `loaded_arr ` `=` `gfg.loadtxt(` `"geekfile.txt"` `)` ` ` `# This loadedArr is a 2D array, therefore` `# we need to convert it to the original` `# array shape.reshaping to get original` `# matrice with original shape.` `load_original_arr ` `=` `loaded_arr.reshape(` ` ` `loaded_arr.shape[` `0` `], loaded_arr.shape[` `1` `] ` `/` `/` `arr.shape[` `2` `], arr.shape[` `2` `])` ` ` `# check the shapes:` `print` `(` `"shape of arr: "` `, arr.shape)` `print` `(` `"shape of load_original_arr: "` `, load_original_arr.shape)` ` ` `# check if both arrays are same or not:` `if` `(load_original_arr ` `=` `=` `arr).` `all` `():` ` ` `print` `(` `"Yes, both the arrays are same"` `)` `else` `:` ` ` `print` `(` `"No, both the arrays are not same"` `)` |

**Output:**

shape of arr: (5, 4, 3) shape of load_original_arr: (5, 4, 3) Yes, both the arrays are same

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