Selecting elements from list of two arrays

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I have the following list of two arrays:

l=[array([16, 19]), array([24, 17])]

How one make new lists to have

#[16,24] and [19,17]

I have tried l[0] and l[1] but those just give me [array([16, 19])] and [array([24, 17])] respectively.

Use .tolist() method from numpy

Ex:

import numpy as np
l=[np.array([16, 19]), np.array([24, 17])]
print([i.tolist() for i in l])

Selecting elements from two arrays to get a target sum, Here is an algorithm using dynamic programming. Let us define the function C:V×​N→N as C(i,s)=r, if using only the first i indices we can achieve a sum of at  Python Numpy : Select elements or indices by conditions from Numpy Array; Python Numpy : Create a Numpy Array from list, tuple or list of lists using numpy.array() How to Reverse a 1D & 2D numpy array using np.flip() and [] operator in Python; Delete elements from a Numpy Array by value or conditions in Python

As I stated in the comments, this is the transpose operation.

import numpy as np
l=[np.array([16, 19]), np.array([24, 17])]

a, b = np.transpose(l)
print(a)
print(b)

# [16 24]
# [19 17]

numpy.select, condlist : list of bool ndarrays. The list of conditions which determine from which array in choicelist the output elements are taken. When multiple conditions are  Select elements from Numpy Array which are greater than 5 and less than 20: Here we need to check two conditions i.e. element > 5 and element < 20. But python keywords and , or doesn’t works with bool Numpy Arrays. Instead of it we should use & , | operators i.e. arr > 5 returns a bool numpy array and arr < 20 returns an another bool numpy array.

You can use a combination of zip and map:

list(map(list, zip(*l)))
# [[16, 24], [19, 17]]

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Python Numpy : Select elements or indices by conditions from , Select elements from a Numpy array based on Single or Multiple Conditions. Let's apply < operator on above created numpy array i.e.. To slice elements from two-dimensional arrays, you need to specify both a row index and a column index as [row_index, column_index]. For example, you can use the index [1,2] to query the element at the second row, third column in precip_2002_2013. # Select element in 2nd row, 3rd column precip_2002_2013 [ 1, 2 ] 1.72

Fancy Indexing, In this section, we'll look at another style of array indexing, known as fancy it means passing an array of indices to access multiple array elements at once. One common use of fancy indexing is the selection of subsets of rows from a matrix. Method #2 : Using islice() + reversed(). The inbuilt funtions can also be used to perform this particular task. The islice function can be used to get the sliced list and reversed function is used to get the elements from rear end.

18 Most Common Python List Questions, Discover how to create a list in Python, select list elements, the difference To Get An Intersection Of Two Lists; How To Remove Duplicates From A List How To Create Empty NumPy Arrays; How To Do Math With Lists. Hi, I would like to get the value and index of elements from a cell array. For instant, I wanted to get the values and indices of the elements which falls within the range 0.95< x <1.15 from the row 'data{1,1}(:,5)'.

Comments
  • Can you make sure your list is n x 2 ? That is each item in the array contains exactly 2 integers?
  • Not sure it works with numpy arrays, but you can try zip(*l)
  • This also seems a lot like the transpose operation.
  • Indexing a list works the same whether the contents are lists or arrays. l[0] is just the first element of the list, not the first element of the all the elements.
  • Thanks just an small edit: print([i.tolist() for i in l[0]]) or print([i.tolist() for i in l[1]]) to complete the answer to my question
  • What is Big..?