ValueError: cannot reshape array of size 300 into shape (100,100,3)

Question

I'm struggeling in reshaping my image. Which is of dimension (100,100,3). The total array for all images makes up (3267, 100, 3)

def get_batch(batch_size,s="train"):
    """Create batch of n pairs, half same class, half different class"""
    if s == 'train':
        X = Xtrain
        X= X.reshape(-1,100,100,3)
        #X= X.reshape(-1,20,105,105)
        categories = train_classes
    else:
        X = Xval
        X= X.reshape(-1,100,100,3)
        categories = val_classes
    n_classes, n_examples, w, h, chan = X.shape
    print(n_classes)
    print(type(n_classes))
    print(n_classes.shape)
    # randomly sample several classes to use in the batch
    categories = rng.choice(n_classes,size=(batch_size,),replace=False)
    
    # initialize 2 empty arrays for the input image batch
    pairs=[np.zeros((batch_size, h, w,1)) for i in range(2)]
    
    # initialize vector for the targets
    targets=np.zeros((batch_size,))
    
    # make one half of it '1's, so 2nd half of batch has same class
    targets[batch_size//2:] = 1
    for i in range(batch_size):
        category = categories[i]
        idx_1 = rng.randint(0, n_examples)
        pairs[0][i,:,:,:] = X[category, idx_1].reshape(w, h, chan)
        idx_2 = rng.randint(0, n_examples)
        
        # pick images of same class for 1st half, different for 2nd
        if i >= batch_size // 2:
            category_2 = category  
        else: 
            # add a random number to the category modulo n classes to ensure 2nd image has a different category
            category_2 = (category + rng.randint(1,n_classes)) % n_classes
        
        pairs[1][i,:,:,:] = X[category_2,idx_2].reshape(w, h,1)
    
    return pairs, targets

However when trying to reshape the array pairs[0][i,:,:,:] = X[category, idx_1].reshape(w, h, chan) I always obtain the error that an array size of 300 is not reshapable into (100,100,3). I honestly don't see the problem why it should be... Can anybody help me out?

faheem faheem · Accepted Answer · 2020-12-09T13:05:30

you want array of 300 into 100,100,3. it cannot be because (100*100*3)=30000 and 30000 not equal to 300 you can only reshape if output shape has same number of values as input.

i suggest you should do (10,10,3) instead because (10*10*3)=300

ValueError: cannot reshape array of size 300 into shape (100,100,3)

1 Answers