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I have an array of arrays

a = np.array([[11, 12, 13, 14],
           [15, 16, 17, 18],
           [19, 20, 21, 22]])

I want to make a loop to extract each row so final result would be

a(1) = [11, 12, 13, 14]
a(2) = [15, 16, 17, 18]
a(3) = [19, 20, 21, 22]

then reshape each a(i) into 2x2 fortran array

a(1) = np.array([[11, 13],
                 [12, 14])
a(2) = np.array([[15, 17],
                 [16, 18])
a(3) = np.array([[19, 21],
                 [20, 22])

Using list comprehension. Please note that a(1) is not the way to access elements in python. Also, the index starts from 0. You can now print a[0], a[1] and so on.

a=[i.reshape((2,2)).T for i in a] # Update after your comment

Output

[array([[11, 13],
    [12, 14]]), array([[15, 17],
    [16, 18]]), array([[19, 21],
    [20, 22]])]

Iterating Numpy Arrays, To iterate each cell in the two-dimensional array, nest the for loop. 1 2 3 for row in A: for  Lists of String Array in Python. Below are the lists of a String array in Python: 1. List. When there is a need for order and also there is a requirement of frequent change, then we prefer selecting the list. Another feature of the list is it allows duplicates. Here is a simple example of a list. Code:

Here you go:

In [4]: a
Out[4]: 
array([[11, 12, 13, 14],
       [15, 16, 17, 18],
       [19, 20, 21, 22]])

In [5]: a[0]
Out[5]: array([11, 12, 13, 14])

In [6]: a[1]
Out[6]: array([15, 16, 17, 18])

In [7]: a[2]
Out[7]: array([19, 20, 21, 22])

In [9]: a[0].reshape(2,2).T
Out[9]: 
array([[11, 13],
       [12, 14]])

In [13]: for i in a:
    ...:     print(i.reshape(2,2).T)
    ...:     
    ...:     
[[11 13]
 [12 14]]
[[15 17]
 [16 18]]
[[19 21]
 [20 22]]

Python Arrays, Looping Array Elements. You can use the for in loop to loop through all the elements of an array. Example. Print each item in  In this article, you’ll learn about Python arrays, difference between arrays and lists, and how and when to use them with the help of examples. In programming, an array is a collection of elements of the same type. Arrays are popular in most programming languages like Java, C/C++, JavaScript and so on. However, in Python, they are not that

Just do the following:

for ele in a:
    print(ele.reshape(2,2))

Or you can use:

for i in range(len(a)):
    print(a[i].reshape(2,2))

Also, in the above please remember that, a(i) is invalid. You need to write a[i].

How to create an array from the list of arrays in python, This post from stack overflow should give you what you want. The magic code boils down to the following. flat_list = [item for sublist in l for item  Note: Python does not have built-in support for Arrays, but Python Lists can be used instead. An array is a special variable, which can hold more than one value at a time. If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this: However, what if you want to loop through the cars

you can directly iterate it using for loop.
import numpy as np

a = np.array([[11, 12, 13, 14],
           [15, 16, 17, 18],
           [19, 20, 21, 22]])

b = list()
for i in range(a.shape[0]):
    b.append(a[i].reshape(2,2))
for itr in b:
    print(b[i])

Look Ma, No For-Loops: Array Programming With NumPy – Real , Getting into Shape: Intro to NumPy Arrays; What is Vectorization? Each image is a three-dimensional array of (height, width, channels) , where the this consists of extracting smaller overlapping sub-arrays from a larger array and can be  In a previous tutorial, we covered the basics of Python for loops, looking at how to iterate through lists and lists of lists.But there’s a lot more to for loops than looping through lists, and in real-world data science work, you may want to use for loops with other data structures, including numpy arrays and pandas DataFrames.

One can use zip with a shift for each list. map is needed to turn the zipped tuples into lists.

>>>[list(map(list,zip(l,l[2:]))) for l in a]   

[[[11, 13], [12, 14]], [[15, 17], [16, 18]], [[19, 21], [20, 22]]]

Boolean or “mask” index arrays, Unlike lists and tuples, numpy arrays support multidimensional indexing for That is, each index specified selects the array corresponding to the rest of the It is possible to slice and stride arrays to extract arrays of the same number of tool that allow one to avoid looping over individual elements in arrays and thus greatly  To process 2-dimensional array, you typically use nested loops. The first loop iterates through the row number, the second loop runs through the elements inside of a row. For example, that's how you display two-dimensional numerical list on the screen line by line, separating the numbers with spaces:

Python Arrays (array module) (With Examples), If you create arrays using the array module, all elements of the array must be of the same numeric type. import array as arr # Error a = arr.array('d', [1, 3.5, "Hello"​]). From Lists to 1-D Numpy Arrays. Numpy is a fast Python library for performing mathematical operations. The numpy class is the “ndarray” is key to this framework; we will refer to objects from this class as a numpy array. Some key differences between lists include, numpy arrays are of fixed sizes, they are homogenous I,e you can only contain

Arrays in Python: What are Python Arrays & How to use them , When we use for loop without any specific parameters, the result contains all the elements of the array given  Know how to create arrays : array, arange, ones, zeros. Know the shape of the array with array.shape, then use slicing to obtain different views of the array: array[::2], etc. Adjust the shape of the array using reshape or flatten it with ravel. Obtain a subset of the elements of an array and/or modify their values with masks >>>

Ways of iterating over a array in JavaScript., Arrays in Javascripts, are single variables used to store different kind of elements. There are multiple ways one can iterate over an array in Javascript. Two dimensional array is an array within an array. It is an array of arrays. In this type of array the position of an data element is referred by two indices instead of one. So it represents a table with rows an dcolumns of data. In the below example of a two dimensional array, observer that each array element itself is also an array.

Comments
  • Thanks for your answer. However, is there anyway to create a loop that separates each row and store them in that manner? as a[0], a[1],...., a[i] since I have +600 record
  • My answer exactly does what you are saying. It is storing as a[0], a[1] and so on. You can think of it as a being the big shelf and [0], [1] and so on being the drawers of that shelf.
  • Sorry for the confusion. I mean in an individual arrays, so a[0], a[1], and a[2] each are an individual array
  • Again confusing. In my answer above, a[0] is an individual array. What you are saying doesn't make sense to me because a[0] a[1] etc all can be individual arrays BUT they still belong to an array or list which is a.
  • My bad, you're right. How can I solve the "AttributeError: 'tuple' object has no attribute 'T'" error when using reshape((2, 2).T? I want the resultant array to be sorted in fortran manner. so output to be [array([[11, 13], [12, 14]]), array([[15, 17], [16, 18]]), array([[19, 21], [20, 22]])]
  • Thanks for your fast respond, I have a set of +600 array, is there any way to make a loop that separate each row/array into a[i] instead of defining each one?
  • Thanks for your answer. However, is there anyway to create a loop that separates each row and store them in that manner? as a[0], a[1],...., a[i] since I have +600 record
  • Is there any certain number of indexes that you want to use? Can you please specify how yyou want to use them? Maybe then I could help...
  • Thanks for your answer. However, is there anyway to create a loop that separates each row and store them in that manner? as a[0], a[1],...., a[i] since I have +600 record
  • I updated my answer it will help you and now you can perform on list b.