## 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] Out[4]: 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=np.array([[1,2,3,4,5],[6,7,8,9,10],[11,12,13,14,15]]) a = a[:,0:3] print(a) #Output #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 tibco.com. 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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