Python: turns string into array

Question

I have a code and am unable to append a variable that was a string, to an array to set of arrays My code:

import face_recognition
import numpy as np

a = face_recognition.load_image_file('C:\\Users\zivsi\OneDrive\תמונות\סרט צילום\WIN_20191115_10_32_24_Pro.jpg')  # my picture 1
a_encodings = face_recognition.face_encodings(a)[0]

b = face_recognition.load_image_file('C:\\Users\zivsi\OneDrive\תמונות\סרט צילום\WIN_20191115_09_48_56_Pro.jpg')  # my picture 2
b_encodings = face_recognition.face_encodings(b)[0]


unknown = face_recognition.load_image_file('C:\\Users\zivsi\OneDrive\תמונות\סרט צילום\WIN_20191117_16_19_11_Pro.jpg')
unknown_encodings =  face_recognition.face_encodings(unknown)[0]




print(type(b_encodings))    # This shows that the variable is an array type
b_encodings = str(b_encodings)    # I make the array variable, a string
b_encodings = np.array(b_encodings)    # I'm trying to turn the string back into the array
print(type(b_encodings))    # It writes that the variable really turned back into an array


results = face_recognition.compare_faces([a_encodings, b_encodings], unknown_encodings, tolerance=0.4) # Here's the problem, it doesn't read it as an array and displays an error

print(results)

Answer 1

I have no experience with numpy but here's my guess for what is happening.

1. b_encodings is initially an array like [1, 2, 3]
2. Then you set b_encodings to the string of itself which is "[1, 2, 3]"
3. You ask for np.array of this, but in the NumPy documentation it says this argument should be array-like. The string you are giving it is array-like, since

list("[1, 2, 3]") == ['[', '1', ',', ' ', '2', ',', ' ', '3', ']']

So the final b_encodings is now this array of the components of an array as a string.

[1, 2, 3] !== ['[', '1', ',', ' ', '2', ',', ' ', '3', ']']

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I don't understand why you ever want to convert the actual array data into a string, only to convert it back later.

If you want to print it, it will probably get converted automatically to a string. If not, you can convert it inline. If you really need a variable with it as a string, you can create a new one.

If you need to store the array (in a file), you could dump it with pickle or write one line per item to a file.