Converting String Column Data to Number

Hi everyone, i wanna ask. So i have a data readed by using this code :

filename = 'D:\KULIAH PASCASARJANA ITB\Bimbingan Tesis\abk198911dmin.txt';
startRow = 14;
formatSpec = '%10{yyyy-MM-dd}D%13s%4f%13f%10f%10f%f%[^\n\r]';
fileID = fopen(filename,'r');
textscan(fileID, '%[^\n\r]', startRow-1, 'WhiteSpace', '', 'ReturnOnError', false, 'EndOfLine', '\r\n');
dataArray = textscan(fileID, formatSpec, 'Delimiter', '', 'WhiteSpace', '', 'TextType', 'string', 'EmptyValue', NaN, 'ReturnOnError', false);
dataArray{2} = strtrim(dataArray{2});
fclose(fileID);
DATE = dataArray{:,1};
TIME = dataArray{:,2};
DOY = dataArray{:,3};
ABKX = dataArray{:,4};
ABKY = dataArray{:,5};
ABKZ = dataArray{:,6};
ABKF = dataArray{:,7};
d = str2double (TIME);
c = str2double(strrep(TIME,':',''));
for i = 1:length(c)
    Converted1 = sprintf('%c%c:%c%c:%s', c(i));
    Converted2 = [c(1:2), ':', c(3:4), ':', c(5:10)];
end

I cant stop thinking how to make the TIME data column to become number data format by using this format 'hh:mm:ss' because it is a string data format which cannot be able to be converted to number format by me. I have tried so many times by using that c variable (str2double(strrep(TIME,':',''))) and the other, but it doesnt work. So please help me out everyone, thank you very much.

If the string formatted TIME data column had been converted to become number format (hh:mm:ss) so then i can plot it....

Answer 1

[Walter Roberson]

Why go through all that trouble?

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/666885/abk198911dmin.txt';
T = readtable(filename, 'headerlines', 12, 'variablenamingrule', 'preserve');
T.DT = T.DATE + T.TIME;
ABKX = T{:,4};

plot(T.DT, ABKX)

[Tyann Hardyn]

Ummm,, im sorry Sir. But it is still error in my matlab... Here is the report :

Error in lemi (line 6)
T = readtable('abk198911dmin.txt', 'headerlines', 12, 'variablenamingrule', 'preserve');

[Tyann Hardyn]

Why it doesnt work in my Matlab???

[Walter Roberson]

Which MATLAB version are you using? I suspect that it might be older than the variablerenamingrule option, but if so then it might also be older than duration parsing.

[Tyann Hardyn]

@Walter Roberson , Im using Matlab R2019.a (9.6.0.1072779). I dont know whether it support that variablenamingrule or not, but its 2019 version, Sir. It is not that old.

[Walter Roberson]

in that case I think you can just remove the 'variablerenamingrule' option.

Answer 2

[Scott MacKenzie]

No need to use textscan. Just read the data into a MATLAB table. The 2nd column (TIME) will be treated as durations. You can then use the hours function to get the time as a number for plotting. Here's a quick demo:

f = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/666885/abk198911dmin.txt';
T = readtable(f);
head(T)
T.TIME(1:5)
hours = hours(T.TIME(1:5))

Output:

ans =

8×8 table

DATE TIME DOY ABKX ABKY ABKZ ABKF x_

__________ ________ ___ _____ ____ _____ _____ ___

1989-11-01 00:00:00 305 11575 746 51129 99999 NaN

1989-11-01 00:01:00 305 11575 747 51132 99999 NaN

1989-11-01 00:02:00 305 11576 750 51134 99999 NaN

1989-11-01 00:03:00 305 11576 749 51135 99999 NaN

1989-11-01 00:04:00 305 11575 750 51137 99999 NaN

1989-11-01 00:05:00 305 11572 752 51137 99999 NaN

1989-11-01 00:06:00 305 11583 753 51135 99999 NaN

1989-11-01 00:07:00 305 11579 751 51137 99999 NaN

ans =

5×1 duration array

00:00:00

00:01:00

00:02:00

00:03:00

00:04:00

hours =

0

0.016667

0.033333

0.05

0.066667

[Tyann Hardyn]

Thank you very much, Sir.... it helped me a lot