How to select row or column from a matrix?

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Here I have a matrix a=np.array([[1,2,3,4,5],[6,7,8,9,10],[11,12,13,14,15]])

I want to select all rows, but the column I want to select is from the first to the third one.

It should be [[1,2,3],[6,7,8],[11,12,13]]

However, I have ever tried a[:,[0,2]], but it shows

 array([[ 1,  3],
       [ 6,  8],
       [11, 13]]) 

It seems not the correct, so I tried another one a[:][0:2], it still is a wrong result.

So I want to ask if there are any function or method can fix the problem?

Sounds like you are looking for a[:, 0:3]:

In [4]: a[:, 0:3]
array([[ 1,  2,  3],
       [ 6,  7,  8],
       [11, 12, 13]])

How to select particular rows from a large matrix ?, Indexing into a matrix is a means of selecting a subset of elements from the matrix. notation for 1:end and is often used to select entire rows or columns: A(​3  Select a Sub Matrix or 2d Numpy Array from another 2D Numpy Array. To select sub 2d Numpy Array we can pass the row & column index range in [] operator i.e. It will return a sub 2D Numpy Array for given row and column range.

I think need indexing 0:3:

print (a[:,0:3])
[[ 1  2  3]
 [ 6  7  8]
 [11 12 13]]

Matrix Indexing in MATLAB - MATLAB & Simulink, How do you clearly select a row or column from a matrix? I know X=(xij)  Similar to vectors, you can use the square brackets [ ] to select one or multiple elements from a matrix. Whereas vectors have one dimension, matrices have two dimensions. You should therefore use a comma to separate the rows you want to select from the columns. For example: my_matrix[1,2] selects the element at the first row and second column.

Try the following

a = a[:,0:3] 
#array([[ 1,  2,  3],
#   [ 6,  7,  8],
#   [11, 12, 13]])

Notation to select column from matrix, [R] Selecting rows/columns of a matrix. William Dunlap wdunlap at Sun Oct 26 19:56:37 CET 2014. Previous message: [R] Injecting a column of  matrices - Notation to select column from matrix - Mathematics Stack Exchange Consider a matrix $X \in \mathbb{R}_{n \times m}$. One compact yet unclear notation to select a row or column from this matrix is: $$x \in X$$ How do you clearly select a row or column from a ma

[R] Selecting rows/columns of a matrix, If our matrix has row names and column names, we can also refer to rows and An index like [4, 2] selects a single element of a matrix, but we can select whole  How to delete multiple row and column in matrix A and Delete row and column specified in matrix B?????/ Follow 151 views (last 30 days)

Working with data in a matrix, If we assign names to the rows and columns of the matrix, than we can access the elements by names. > dimnames(A) = list( + c("row1", "row2"), # row names Select a Web Site. Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: . Select web site

Matrix, Elements to select can be a an element only or single/multiple rows & columns or an another sub 2D array. First of all, let's import numpy  To get the second element in the third column, you need to do the following: Count the number of rows, using nrow(), and store that in a variable — for example nr. You don’t have to do this, but it makes the code easier to read. Count two columns and then add 2 to get the second element in the third column.

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