How to find the sum and product of a 2-D array in Python
Maria ElijahOverview
The Python library NumPy has the methods sum() and product(), which can be used to find the sum and product of array elements.
The numpy.sum() method
Syntax
numpy.sum(arr, axis=None, dtype=None, out=None)
Return value
The numpy.sum() method returns the sum of elements in a given input array over a specified axis.
The numpy.prod() method
Syntax
numpy.prod(arr, axis=None, dtype=None, out=None)
Return value
The numpy.prod() method returns the product of elements in a given input array over a specified axis.
Note: A 2-D array can be created using a list of lists in Python.
Parameters
arr: This is anarray_likeobject that represents the input data.axis: This is an optional parameter. It represents the axes along which the operation is to be performed.dtype: This is an optional parameter. It represents the return type of the array.out: This is an optional parameter. It represents the alternative output array in which the result is to be placed.
Note: If the
outparameter is specified, it returns an array reference toout.
Examples
The following code snippets show how to find the sum and product of the 2-D array using the numpy.sum() and numpy.prod() methods.
Example 1
Find the sum of a 2-D array using the numpy.sum() method.
# import numpy import numpy as np # create a list my_list1 = [24,8,3,4,34,8] my_list2 = [5,7,2,10,15,7] # convert to a numpy 2D array np_list = np.array([my_list1, my_list2]) # compute the sum of array elements and store it np_list_sum = np.sum(np_list, axis=0) print(np_list_sum)
Explanation
- Line 2: We import the
numpylibrary. - Line 4–5: We create two lists called
my_list1andmy_list2. - Line 7: We convert the lists to a NumPy array which gives us a 2-D array. Then, the value is stored in a variable called
np_list. - Line 9: We use the
np.sum()to compute the sum of elements in thenp_list. - Line 11: We display the result.
Example 2
Find the product of a 2-D array using the numpy.product() method.
# import numpy import numpy as np # create a list my_list1 = [24,8,3,4,8] my_list2 = [5,7,2,10,7] # convert to a numpy 2D array np_list = np.array([my_list1, my_list2]) # compute the product of 2D array # and store the result in np_list_cumprod np_list_prod = np.prod(np_list, axis=0) print(np_list_prod)
Explanation
- Line 2: We import the
numpylibrary. - Line 4–5: We create two lists called
my_list1andmy_list2. - Line 7: We convert the lists to a NumPy array which gives us a 2-D array. Then, we store the value in a variable called
np_list. - Line 10: We use the
np.prod()to compute the product of elements in thenp_list. - Line 11: We display the result.
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