Reading data in MATLAB

Hello,

just wanted to plot data from .txt-file as below:

T = readtable('data_Labor1_CH1_AnAusSpannung.txt','VariableNamingRule','preserve')

T = 1200x3 table
    NO.        Voltage(NL3)              Time(NL3)       
    ___    ____________________    ______________________

     1     {'-9,60 \cdot 10^3'}    {'-1,1980 \cdot 10^2'}
     2     {'-1,12 \cdot 10^2'}    {'-1,1960 \cdot 10^2'}
     3     {'-9,60 \cdot 10^3'}    {'-1,1940 \cdot 10^2'}
     4     {'-9,60 \cdot 10^3'}    {'-1,1920 \cdot 10^2'}
     5     {'-9,60 \cdot 10^3'}    {'-1,1900 \cdot 10^2'}
     6     {'-9,60 \cdot 10^3'}    {'-1,1880 \cdot 10^2'}
     7     {'-9,60 \cdot 10^3'}    {'-1,1860 \cdot 10^2'}
     8     {'-9,60 \cdot 10^3'}    {'-1,1840 \cdot 10^2'}
     9     {'-9,60 \cdot 10^3'}    {'-1,1820 \cdot 10^2'}
    10     {'-1,04 \cdot 10^2'}    {'-1,1800 \cdot 10^2'}
    11     {'-1,04 \cdot 10^2'}    {'-1,1780 \cdot 10^2'}
    12     {'-1,12 \cdot 10^2'}    {'-1,1760 \cdot 10^2'}
    13     {'-9,60 \cdot 10^3'}    {'-1,1740 \cdot 10^2'}
    14     {'-1,04 \cdot 10^2'}    {'-1,1720 \cdot 10^2'}
    15     {'-9,60 \cdot 10^3'}    {'-1,1700 \cdot 10^2'}
    16     {'-1,04 \cdot 10^2'}    {'-1,1680 \cdot 10^2'}

t = T.("Time(NL3)");
U = T.("Voltage(NL3)")

U = 1200x1 cell array
    {'-9,60 \cdot 10^3'}
    {'-1,12 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,12 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-8,80 \cdot 10^3'}
    {'-8,80 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}

figure()
plot(t,U,'b','LineWidth',2),hold on, grid on;

Error using plot
Invalid data argument.

Then it goes:

Error using plot

Invalid data argument.

Error in Untitled (line 7)

plot(t,U,'b','LineWidth',2),hold on, grid on;

What could I do wrong? Thanks.

Answer 1

[Star Strider]

Try this —

% T = readtable('data_Labor1_CH1_AnAusSpannung.txt','VariableNamingRule','preserve')
T = readtable('data_Labor1_CH...sSpannung.txt','VariableNamingRule','preserve')

T = 1200x3 table
    NO.        Voltage(NL3)              Time(NL3)       
    ___    ____________________    ______________________

     1     {'-9,60 \cdot 10^3'}    {'-1,1980 \cdot 10^2'}
     2     {'-1,12 \cdot 10^2'}    {'-1,1960 \cdot 10^2'}
     3     {'-9,60 \cdot 10^3'}    {'-1,1940 \cdot 10^2'}
     4     {'-9,60 \cdot 10^3'}    {'-1,1920 \cdot 10^2'}
     5     {'-9,60 \cdot 10^3'}    {'-1,1900 \cdot 10^2'}
     6     {'-9,60 \cdot 10^3'}    {'-1,1880 \cdot 10^2'}
     7     {'-9,60 \cdot 10^3'}    {'-1,1860 \cdot 10^2'}
     8     {'-9,60 \cdot 10^3'}    {'-1,1840 \cdot 10^2'}
     9     {'-9,60 \cdot 10^3'}    {'-1,1820 \cdot 10^2'}
    10     {'-1,04 \cdot 10^2'}    {'-1,1800 \cdot 10^2'}
    11     {'-1,04 \cdot 10^2'}    {'-1,1780 \cdot 10^2'}
    12     {'-1,12 \cdot 10^2'}    {'-1,1760 \cdot 10^2'}
    13     {'-9,60 \cdot 10^3'}    {'-1,1740 \cdot 10^2'}
    14     {'-1,04 \cdot 10^2'}    {'-1,1720 \cdot 10^2'}
    15     {'-9,60 \cdot 10^3'}    {'-1,1700 \cdot 10^2'}
    16     {'-1,04 \cdot 10^2'}    {'-1,1680 \cdot 10^2'}

t = T.("Time(NL3)")

t = 1200x1 cell array
    {'-1,1980 \cdot 10^2'}
    {'-1,1960 \cdot 10^2'}
    {'-1,1940 \cdot 10^2'}
    {'-1,1920 \cdot 10^2'}
    {'-1,1900 \cdot 10^2'}
    {'-1,1880 \cdot 10^2'}
    {'-1,1860 \cdot 10^2'}
    {'-1,1840 \cdot 10^2'}
    {'-1,1820 \cdot 10^2'}
    {'-1,1800 \cdot 10^2'}
    {'-1,1780 \cdot 10^2'}
    {'-1,1760 \cdot 10^2'}
    {'-1,1740 \cdot 10^2'}
    {'-1,1720 \cdot 10^2'}
    {'-1,1700 \cdot 10^2'}
    {'-1,1680 \cdot 10^2'}
    {'-1,1660 \cdot 10^2'}
    {'-1,1640 \cdot 10^2'}
    {'-1,1620 \cdot 10^2'}
    {'-1,1600 \cdot 10^2'}
    {'-1,1580 \cdot 10^2'}
    {'-1,1560 \cdot 10^2'}
    {'-1,1540 \cdot 10^2'}
    {'-1,1520 \cdot 10^2'}
    {'-1,1500 \cdot 10^2'}
    {'-1,1480 \cdot 10^2'}
    {'-1,1460 \cdot 10^2'}
    {'-1,1440 \cdot 10^2'}
    {'-1,1420 \cdot 10^2'}
    {'-1,1400 \cdot 10^2'}

U = T.("Voltage(NL3)")

U = 1200x1 cell array
    {'-9,60 \cdot 10^3'}
    {'-1,12 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,12 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-1,04 \cdot 10^2'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-8,80 \cdot 10^3'}
    {'-8,80 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}
    {'-9,60 \cdot 10^3'}

t = strrep(t, ',','.');
t = strrep(t, '10^','E');
t = str2double(cellfun(@(x)sscanf(x, '%s \\cdot %s'), t, 'Unif',0))

t = 1200×1

-119.8000 -119.6000 -119.4000 -119.2000 -119.0000 -118.8000 -118.6000 -118.4000 -118.2000 -118.0000

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U = strrep(U, ',','.');
U = strrep(U, '10^','E');
U = str2double(cellfun(@(x)sscanf(x, '%s \\cdot %s'), U, 'Unif',0))

U = 1200×1

-9600 -112 -9600 -9600 -9600 -9600 -9600 -9600 -9600 -104

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figure()
plot(t,U,'b','LineWidth',2),hold on, grid on;

.

[Alisa-Oleksandra Kotliarova]

Thanks a lot=)

[Star Strider]

My pleasure!

Answer 2

[Cris LaPierre]

The numbers are not captured in a format MATLAB can interpret. I would apply post-processing to turn the captured char arrays to a number format recognized by MATLAB.

file = 'data_Labor1_CH1_AnAusSpannung.txt';
data = readtable(file,'VariableNamingRule','preserve')

data = 1200x3 table
    NO.        Voltage(NL3)              Time(NL3)       
    ___    ____________________    ______________________

     1     {'-9,60 \cdot 10^3'}    {'-1,1980 \cdot 10^2'}
     2     {'-1,12 \cdot 10^2'}    {'-1,1960 \cdot 10^2'}
     3     {'-9,60 \cdot 10^3'}    {'-1,1940 \cdot 10^2'}
     4     {'-9,60 \cdot 10^3'}    {'-1,1920 \cdot 10^2'}
     5     {'-9,60 \cdot 10^3'}    {'-1,1900 \cdot 10^2'}
     6     {'-9,60 \cdot 10^3'}    {'-1,1880 \cdot 10^2'}
     7     {'-9,60 \cdot 10^3'}    {'-1,1860 \cdot 10^2'}
     8     {'-9,60 \cdot 10^3'}    {'-1,1840 \cdot 10^2'}
     9     {'-9,60 \cdot 10^3'}    {'-1,1820 \cdot 10^2'}
    10     {'-1,04 \cdot 10^2'}    {'-1,1800 \cdot 10^2'}
    11     {'-1,04 \cdot 10^2'}    {'-1,1780 \cdot 10^2'}
    12     {'-1,12 \cdot 10^2'}    {'-1,1760 \cdot 10^2'}
    13     {'-9,60 \cdot 10^3'}    {'-1,1740 \cdot 10^2'}
    14     {'-1,04 \cdot 10^2'}    {'-1,1720 \cdot 10^2'}
    15     {'-9,60 \cdot 10^3'}    {'-1,1700 \cdot 10^2'}
    16     {'-1,04 \cdot 10^2'}    {'-1,1680 \cdot 10^2'}

% I find strings are easier to work with
data = convertvars(data,@iscell,'string');
% replace the expression with scientific notation (replaces the decimal separator, too)
clnFxn = @(x) str2double(replace(replace(x,' \cdot 10^','E'),',','.'));
data(:,vartype('string')) = varfun(clnFxn,data,'InputVariables',@isstring)

data = 1200x3 table
    NO.    Voltage(NL3)    Time(NL3)
    ___    ____________    _________

     1       "-9600"       "-119.8" 
     2       "-112"        "-119.6" 
     3       "-9600"       "-119.4" 
     4       "-9600"       "-119.2" 
     5       "-9600"       "-119"   
     6       "-9600"       "-118.8" 
     7       "-9600"       "-118.6" 
     8       "-9600"       "-118.4" 
     9       "-9600"       "-118.2" 
    10       "-104"        "-118"   
    11       "-104"        "-117.8" 
    12       "-112"        "-117.6" 
    13       "-9600"       "-117.4" 
    14       "-104"        "-117.2" 
    15       "-9600"       "-117"   
    16       "-104"        "-116.8" 

% Convert table variables to double
data = convertvars(data,@isstring,'double')

data = 1200x3 table
    NO.    Voltage(NL3)    Time(NL3)
    ___    ____________    _________

     1        -9600         -119.8  
     2         -112         -119.6  
     3        -9600         -119.4  
     4        -9600         -119.2  
     5        -9600           -119  
     6        -9600         -118.8  
     7        -9600         -118.6  
     8        -9600         -118.4  
     9        -9600         -118.2  
    10         -104           -118  
    11         -104         -117.8  
    12         -112         -117.6  
    13        -9600         -117.4  
    14         -104         -117.2  
    15        -9600           -117  
    16         -104         -116.8  

% Plot
t = data.("Time(NL3)");
U = data.("Voltage(NL3)");

figure()
plot(t,U,'b','LineWidth',2)
grid on;

[Alisa-Oleksandra Kotliarova]

Thanks a lot