Convert fingerprint to numpy array and convert numpy array to fingerprint #RDKit #memorandum

This is just memorandum for my self.
RDKit has ConvertToNumpyArray method for converting rdkit fp to numpy array. But there is not direct method for convert numpy array to rdkit fp.
However, rdkit has CreateFromBitString method.

So, I tried to convert numpy array to rdkit fp with the method.

import numpy as np
from rdkit import Chem
from rdkit.Chem import AllChem
from rdkit.Chem import DataStructs
mol = Chem.MolFromSmiles('C1CCCOC1')
fp = AllChem.GetMorganFingerprintAsBitVect(mol, 2, nBits=512)
arr = np.zeros((0,), dtype=np.int8)
arr
> array([], dtype=int8)

Then convert fp to numpy array.

DataStructs.ConvertToNumpyArray(fp,arr)
arr
> array([0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

Next convert numpy array to rdkit fp.

bitstring="".join(arr.astype(str))
fp2 = DataStructs.cDataStructs.CreateFromBitString(bitstring)

Finally, check both fingerprint.

list(fp.GetOnBits())
> [2, 4, 11, 28, 144, 225, 381, 414, 438]

list(fp2.GetOnBits())
> [2, 4, 11, 28, 144, 225, 381, 414, 438]

RDKit has many functions. I am happy to find new methods that I have not used before. ;)

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