How to read data from a CSV into a column vector

Question

waleed khalid 2020-11-5

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https://ww2.mathworks.cn/matlabcentral/answers/637660-how-to-read-data-from-a-csv-into-a-column-vector

评论： Monika Jaskolka 2020-11-5

I have 25 csv files that I need to grab data from, they are all in the same format with no headers, I would like to grab all of this data, and store it into a column vector. Previous iterations of this program have used fread(filename, size) to read binary files into a column vector and throw them into a calculation script, I would like to keep the script in the same format so I need to read this csv data into a Column Vector.

I also imported them into a table so if there is a way to convert this table into a Column vector that works too, I am not concerned with the loss of efficiency in terms of runtiime.

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Answer 1

Monika Jaskolka 2020-11-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/637660-how-to-read-data-from-a-csv-into-a-column-vector#answer_535525

编辑：Monika Jaskolka 2020-11-5

在 MATLAB Online 中打开

>> m = readmatrix('test.csv')
m =
     1     2     3     4
     5     6     7     8
>> m = m(:)
m =
     1
     5
     2
     6
     3
     7
     4
     8
     

For mixed data:

>> m = readtable('test.csv')
m =
  2×4 table
    Var1    Var2    Var3     Var4
    ____    ____    _____    ____
     1       2      {'a'}     4  
     5       6      {'b'}     8  
>> m = table2cell(m)
m =
  2×4 cell array
    {[1]}    {[2]}    {'a'}    {[4]}
    {[5]}    {[6]}    {'b'}    {[8]}
>> m = m(:)
m =
  8×1 cell array
    {[1]}
    {[5]}
    {[2]}
    {[6]}
    {'a'}
    {'b'}
    {[4]}
    {[8]}

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waleed khalid 2020-11-5

在 MATLAB Online 中打开

Thanks for that! For some reason, when I call readmatrix(filename), the values in my csv's become obfuscated to this:

0000    0.0000    0.0000   -0.0000    0.0002    0.0000
0000    0.0000    0.0000   -0.0000    0.0002    0.0000
0000    0.0000    0.0000   -0.0000    0.0002    0.0000
0000    0.0000    0.0000   -0.0000    0.0002    0.0000
0000    0.0000    0.0000   -0.0000    0.0002    0.0000

Monika Jaskolka 2020-11-5

The data is there, but Matlab has different formats for displaying data in the Command Window. Read more about it here: https://www.mathworks.com/help/matlab/ref/format.html . The default is "format short", which is only 4 decimal places.

So if you want to see more decimals, type in "format long" into your Command Window, and then try to display the matrix again.

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