Reading CSV files with MATLAB?

Question

I am trying to read in a .csv file with MATLAB. Here is my code:

csvread('out2.csv')

This is what out2.csv looks like:

03/09/2013 23:55:12,129.32,129.33
03/09/2013 23:55:52,129.32,129.33
03/09/2013 23:56:02,129.32,129.33

On windows I am able to read this exact same file with the xlsread function with no problems. I am currently on a linux machine. When I first used xlsread to read the file I was told "File is not in recognized format" so I switched to using csvread. However, using csvread, I get the following error message:

Error using dlmread (line 139)
Mismatch between file and format string.
Trouble reading number from file (row 1u, field 2u) ==> /09/2013
23:55:12,129.32,129.33\n

Error in csvread (line 48)
m=dlmread(filename, ',', r, c)

I think the '/' in the date is causing the issue. On windows, the 1st column is interpreted as a string. On linux it seems to be interpreted as a number, so it tries to read the number and fails at the backslash. This is what I think is going on at least. Any help would be really appreciated.

try readtext instead of csvread.

Autonomous
– Autonomous

2013-10-27 00:07:27 +00:00
Commented Oct 27, 2013 at 0:07 — Autonomous
– Autonomous, Commented Oct 27, 2013 at 0:07

craigim · Accepted Answer · 2017-08-31 13:26:02Z

csvread can only read doubles, so it's choking on the date field. Use textscan.

fid = fopen('out2.csv');
out = textscan(fid,'%s%f%f','delimiter',',');
fclose(fid);

date = datevec(out{1});
col1 = out{2};
col2 = out{3};

Update (8/31/2017)

Since this was written back in 2013, MATLAB's textscan function has been updated to directly read dates and times. Now the code would look like this:

fid = fopen('out2.csv');
out = textscan(fid, '%{MM/dd/uu HH:mm:ss}D%f%f', 'delimiter', ',');
fclose(fid)

[date, col1, col2] = deal(out{:});

An alternative as mentioned by @Victor Hugo below (and currently my personal go-to for this type of situation) would be to use readtable which will accept the same formatting string as textscan but assemble the results directly into a table object:

dataTable = readtable('out2.csv', 'Format', '%{MM/dd/uu HH:mm:ss}D%f%f')
dataTable.Properties.VariableNames = {'date', 'col1', 'col2'};

dataTable =

  3×3 table

           date             col1      col2 
    ___________________    ______    ______

    03/09/2013 23:55:12    129.32    129.33
    03/09/2013 23:55:52    129.32    129.33
    03/09/2013 23:56:02    129.32    129.33

nispio · Accepted Answer · 2013-10-27 00:08:22Z

6

Unfortunately, the documentation for csvread clearly states:

M = csvread(filename) reads a comma-separated value formatted file, filename. The file can only contain numeric values.

Since / is neither a comma, nor a numeric value, it produces an error.

answered Oct 27, 2013 at 0:08

nispio

1,80612 silver badges23 bronze badges

Comments

Victor Hugo · Accepted Answer · 2016-10-24 13:43:44Z

2

You can use readtable, as it will accept any input.

https://www.mathworks.com/help/matlab/ref/readtable.html

answered Oct 24, 2016 at 13:43

Victor Hugo

563 bronze badges

Comments

mechcaptain · Accepted Answer · 2020-04-28 11:26:40Z

0

Yeah xlsread requires Microsoft Excel to be installed, unless it is run in 'basic' mode and 'basic' mode only reads .xls .xlsx and .xlsm files.

Another alternative are a number of user-written functions posted on MATLAB's file exchange that will work on linux and are more flexible at reading non formatted content.

One example: https://www.mathworks.com/matlabcentral/fileexchange/75219-csv2cellfast-import-csv-files-on-machines-without-excel

edited Apr 28, 2020 at 11:26

answered Apr 27, 2020 at 5:32

mechcaptain

134 bronze badges

1 Comment

Borja Over a year ago

This was published as an answer, but does not attempt to answer the question. Please edit your answer and add an explanation that may be useful.

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