I want to append a numpy array(matrix) into an array through a loop

```
data=[[2 2 2] [3 3 3]]
Weights=[[4 4 4] [4 4 4] [4 4 4]]
All=np.array([])
for i in data:
#i=[2 2 2 ] #for example
h=i*Weights
#h=[[8 8 8][8 8 8][8 8 8]]
All=np.concatenate((All,h),axis=0)
```

I ge this error:

```
ValueError: all the input arrays must have same number of dimensions
```

I want "All" variable to be

```
[[8 8 8][8 8 8][8 8 8] [12 12 12][12 12 12][12 12 12]]
```

Any way how I can add "h" to "All" through the loop ?

*Option 1*: Reshape your initial `All`

array to 3 columns so that the number of columns match `h`

:

```
All=np.array([]).reshape((0,3))
for i in data:
h=i*Weights
All=np.concatenate((All,h))
All
#array([[ 8., 8., 8.],
# [ 8., 8., 8.],
# [ 8., 8., 8.],
# [ 12., 12., 12.],
# [ 12., 12., 12.],
# [ 12., 12., 12.]])
```

*Option 2*: Use a if-else statement to handle initial empty array case:

```
All=np.array([])
for i in data:
h=i*Weights
if len(All) == 0:
All = h
else:
All=np.concatenate((All,h))
All
#array([[ 8, 8, 8],
# [ 8, 8, 8],
# [ 8, 8, 8],
# [12, 12, 12],
# [12, 12, 12],
# [12, 12, 12]])
```

*Option 3*: Use `itertools.product()`

:

```
import itertools
np.array([i*j for i,j in itertools.product(data, Weights)])
#array([[ 8, 8, 8],
# [ 8, 8, 8],
# [ 8, 8, 8],
# [12, 12, 12],
# [12, 12, 12],
# [12, 12, 12]])
```