I want to know how I can add a value to each element of a NXN multidimensional array. I tried [x+1 for x in multiArray], but this one yields only for a 1D array.
Maybe something like this:
multiArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
addingArray=[]
for i in range(3):
for j in range(3):
addingArray.append(multiArray[j]+1) #(adding 1 to each element here)
But this seems to be wrong?
You're getting 1D array as result because you have addingArray as a simple list. So, you iterate over all the elements in your multiArray and add 1 to it and you're appending the result to a list.
For efficiency reasons, it is advisable to use NumPy for arrays. Then, you can simply use broadcasting to add value to each element of the array. Below is an illustration:
# input array
In [180]: multiArray = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
# add 1 to each value of the array
In [181]: multiArray + 1
Out[181]:
array([[ 2, 3, 4],
[ 5, 6, 7],
[ 8, 9, 10]])
If you indeed want a plain python list as the result for some reasons, you can simply cast it to one:
In [182]: (multiArray + 1).tolist()
Out[182]: [[2, 3, 4], [5, 6, 7], [8, 9, 10]]
You need to have a inner list to get the inner results, and access the good value with multiArray[i][j], also don't use constant 3 take the habit to use object length
addingArray=[]
for i in range(len(multiArray)):
innerArray = []
for j in range(len(multiArray[i])):
innerArray.append(multiArray[i][j]+1)
addingArray.append(innerArray)
print(addingArray) # [[2, 3, 4], [5, 6, 7], [8, 9, 10]]
You can also iterate over the arra directly to simplify and don't both with indices
addingArray=[]
for inner in multiArray:
innerArray = []
for value in inner:
innerArray.append(value+1)
addingArray.append(innerArray)
And shorten it with list comprehension syntax
multiArray = [[v+1 for v in inner] for inner in multiArray]
print(multiArray) # [[2, 3, 4], [5, 6, 7], [8, 9, 10]]
