Create matrix from 2 columns of a csv file

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Jake 2020-12-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/704267-create-matrix-from-2-columns-of-a-csv-file

评论： Jake 2020-12-30

A CSV file includes all my data in seperate columns and I'm trying to extract them separately for analysis. I'm using MATLAB R2019b, btw.

CSV file looks like the one that I've attached below (Please let me know if an actual csv is needed), it contains following information:

Reference number (numbers - a consistant series)
ID (a unique number)
X, Y (Distances in a cartesia plane - upto 7 decimal points)
Name (A string - not unique, includes numbers, letters and symbols)
Time (a time stamp - I'd love to read it as yyyymmddhhmm, but reading it as date is also fine)
A, B, C, D (numbers - includes decimals)

I can read the data and create the matrix that include all the columns using readmatrix and I can get specific parts from that matrix. But I want to read the CSV file and create separate matrices using separate columns.

For example:

matrix_1 = matrix that includes all data in columns ID and A

matrix_2 = matrix that includes all data in columns ID, X and Y and so on.

How can I approach this, while preserving the data types included in csv? Apologies if my question needs more clarification.

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Adam Danz 2020-12-29

I recommend that you don't split up the table and use table indexing instead. There's rarely a good reason to split up a tidy data set. One exception is if you're trying to reduce the size of your table in memory by eliminating variables you know you'll never need.

Jake 2020-12-29

Thanks, Adam! That's actually a good point. I was going to try creating different matrices but I'm realizing now that I can just use the table instead. Thanks for the advice!

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Answer 1

Adam Danz 2020-12-29

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https://ww2.mathworks.cn/matlabcentral/answers/704267-create-matrix-from-2-columns-of-a-csv-file#answer_586698

Summary of comments under the question:

Use readtable() to import the data
Use table indexing rather than splitting the table into separate variables.

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Image Analyst 2020-12-29

James, if you need more help, attach the CSV file. It's rarely / never a good idea to leave off a data file and then have people have to ask for it afterwards. So for now you'll have to live with hints and partial answers than complete turnkey solutions.

Jake 2020-12-30