csv file import with exponential notation

Hello,

I importet data from a sensor reading and wanted to plot them (force over time)

as the force data contained commata I had to convert them, but I still have a wrong graph as the exponential notation is not 'detected'.

This is my script:

%%read txt file with force measurement, save datevec 
Data = readtable('CSV-file.csv','TextType','string');      %add name of csv file (readtable)
waveform = table2array(Data(:,1));  %table to cell time vector
Y = table2array(Data(:,2));                %save force in waveform

Y([1,2,3,4,5],:) = [];        %delete rows 1-5 force vector
waveform([1,2,3,4,5],:) = [];        %delete rows 1-5 time vector
Data2 = strrep(Y, ',', '.');
Timevector = datetime (waveform ,'InputFormat','dd.MM.yyyy HH:mm:ss,SSSSS');
 Data21 = categorical(Data2(:,1));
plot (Timevector, Data21,'b*');
yyy HH:mm:ss,SSSSS');
 Data21 = categorical(Data2(:,1));
plot (Timevector, Data21,'b*');

my Data (.csv):

and this is my current plot vs. the actual plot:

is there a way to format the string, so that the exponential notation is right?

[Ameer Hamza]

Can you attach some sample datapoints from as a csv file?

Answer 1

[Cris LaPierre]

Here's how I would do it.

%%read txt file with force measurement, save datevec 
opts = detectImportOptions("CSV-file.csv","NumHeaderLines",6);
opts = setvartype(opts,"DateTime","datetime");
opts = setvaropts(opts,"DateTime","InputFormat",'dd.MM.yyyy HH:mm:ss,SSSSS');

opts = setvartype(opts,"Y_Chan_3_","string");

Data = readtable('CSV-file.csv',opts);

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

% specifying the decimal separator didn't help because of the formatting.
% This replaces it with a period. This may not be necessary depending on your regional settings.
Data.Y_Chan_3_ = strrep(Data.Y_Chan_3_,',','.');
Data.Y_Chan_3_ = str2double(Data.Y_Chan_3_)

Data = 3507x2 table
            DateTime             Y_Chan_3_
    _________________________    _________

    21.12.2020 19:21:32,15037    -0.012731
    21.12.2020 19:21:32,25045    -0.012731
    21.12.2020 19:21:32,35054    -0.025462
    21.12.2020 19:21:32,45062    -0.012731
    21.12.2020 19:21:32,55071    -0.012731
    21.12.2020 19:21:32,65079    -0.012731
    21.12.2020 19:21:32,75088    -0.025462
    21.12.2020 19:21:32,85096    -0.025462
    21.12.2020 19:21:32,95105    -0.025462
    21.12.2020 19:21:33,05113    -0.025462
    21.12.2020 19:21:33,15122    -0.012731
    21.12.2020 19:21:33,25130    -0.025462
    21.12.2020 19:21:33,35139    -0.025462
    21.12.2020 19:21:33,45147    -0.038193
    21.12.2020 19:21:33,55156     -0.11458
    21.12.2020 19:21:33,65164     -0.29282

[Thomas Unterholzner]

This worked perfect. Thanks a lot Cris LaPierre!

Answer 2

[Walter Roberson]

Use the decimalseparator option for readtable

https://www.mathworks.com/help/matlab/ref/detectimportoptions.html#d122e302928

I think it became available as of R2020a but that would have to be checked

[Walter Roberson]

You might need Prefix and Suffix to get rid of quote marks