How to extract rows given multiple ranges

2022 5 30
1 个回答
回答已采纳
更新时间：2022 5 30
4 次查看（30 天）

0 个投票

So i have a dataset and I'm trying to downsize it, I have data sorted and have extracted the row indeces required to downsize the dataset while maintaining an almost equal amount of samples per class.
Here are the the specified rows. The dataset has 500,000 samples, using these rows downsizes it to about 120,000. I just want to know what I can to extract these from the original dataset keeping all the columns.
[0:5000,34586:39586,72961:77961,107165:112165,142309:147309,175845:180845,207262:212262,241495:246495,277250:282250,311197:316197,345045:350045,351453:354453,355332:359332,359895:362895,363048:365048,365517:370517,373755:378755,398739:403739,408560:413560,421163:425163,425859:427859,428631:433631,438809:443809,447548:452548,462867:467867,474286:476286,477036:479036,480031:485031,498294:500294]

请先登录，再回答此问题。

 采纳的回答

KSSV
KSSV 2022-5-30
编辑：KSSV 2022-5-30
Ran in:

1 个投票

Ran in:
If you have the indices of rows idx, you can just use
iwant = A(idx,:) ; % where A is your matrix and idx are the row indices
to extract the rows from A wih all the columns.
Note: MATLAB indexing start from 1 and indices should be positive integers or logicals.
In your case, the first number: 0:5000 should be 1:5000.
% EXample
A = magic(10) % dummy data for demo
A = 10×10
92 99 1 8 15 67 74 51 58 40 98 80 7 14 16 73 55 57 64 41 4 81 88 20 22 54 56 63 70 47 85 87 19 21 3 60 62 69 71 28 86 93 25 2 9 61 68 75 52 34 17 24 76 83 90 42 49 26 33 65 23 5 82 89 91 48 30 32 39 66 79 6 13 95 97 29 31 38 45 72 10 12 94 96 78 35 37 44 46 53 11 18 100 77 84 36 43 50 27 59
idx = [1 3 5 7] ; % extrcat these rows from A
iwant = A(idx,:)
iwant = 4×10
92 99 1 8 15 67 74 51 58 40 4 81 88 20 22 54 56 63 70 47 86 93 25 2 9 61 68 75 52 34 23 5 82 89 91 48 30 32 39 66

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Database Toolbox 的更多信息

产品

版本

R2021a

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by