Python get array value by index
I have a numpy array like this: Show
How can I get the values at certain index positions in ONE step? For example:
The result should be:
asked Aug 8, 2014 at 10:31
1 Just index using you
answered Aug 8, 2014 at 10:32
2 The one liner "no imports" version
answered Mar 28, 2017 at 14:46
Ohad CohenOhad Cohen 5,3283 gold badges36 silver badges35 bronze badges Although you ask about
answered Aug 8, 2014 at 12:20
chepnerchepner 460k67 gold badges483 silver badges625 bronze badges 3 You can use index arrays, simply pass your
Index arrays do not necessarily have to be numpy arrays, they can be also be lists or any sequence-like object (though not tuples). answered Aug 8, 2014 at 10:32
FfisegyddFfisegydd 48.8k14 gold badges139 silver badges118 bronze badges your code would be
you get [88, 85, 16]
Joey 1372 silver badges13 bronze badges answered Aug 8, 2014 at 10:34
Elements in NumPy arrays can be accessed by indexing. Indexing is an operation that pulls out a select set of values from an array. The index of a value in an array is that value's
location within the array. There is a difference between the value and where the value is stored in an array. An array with 3 values is created in the code section below. In [1]: a = np.array([2,4,6])
print(a)
2 , 4 and 6 . Each of these values has a different index. Remember counting in Python starts at The value
Individual values stored in an array can be accessed with indexing. The general form to index a NumPy array is below:
Where In the array above, the value 6 is stored at index 2. In [2]: import numpy as np Multi-dimensional Array IndexingMulti-dimensional arrays can be indexed as well. A simple 2-D array is defined by a list of lists. In [3]: import numpy as npValues in a 2-D array can be accessed using the general notation below:
Where We can access the value
In [4]: import numpy as np Assigning Values with IndexingArray indexing is used to access values in an array. And array indexing can also be used for assigning values of an array. The general form used to assign a value to a particular index or location in an array is below:
Where The code below puts the value In [5]: import numpy as npValues can also be assigned to a particular location in a 2-D arrays using the form:
The code example below shows the value In [6]: import numpy as np [[2 3 4] [6 7 8]] [[ 2 3 4] [ 6 7 20]] How do you extract a value from an array in Python?You can use the pop() method to remove an element from the array.
How do you find the index value of an array in Python?Summary:. The list index() method helps you to find the index of the given element. ... . The list index() method returns the index of the given element.. If the element is not present in the list, the index() method will throw an error, for example, ValueError: 'Element' is not in list.. How do you print an array position in Python?PROGRAM:. #Initialize array.. arr = [1, 2, 3, 4, 5];. print("Elements of given array present on even position: ");. #Loop through the array by incrementing the value of i by 2.. #Here, i will start from 1 as first even positioned element is present at position 1.. for i in range(1, len(arr), 2):. print(arr[i]);. Do NumPy arrays have index?You can access an array element by referring to its index number. The indexes in NumPy arrays start with 0, meaning that the first element has index 0, and the second has index 1 etc.
|