How do i reset a fileID value?

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Whale_Shark on 24 Nov 2022

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https://ch.mathworks.com/matlabcentral/answers/1862173-how-do-i-reset-a-fileid-value

Edited: Stephen23 on 25 Nov 2022

Relatively new to MATLAB so it's probably a stupid question. But when writing my code I forgot to use the fclose function in my for loop so the value kept going up. My fid value i believe should be 34 but shows as 54 (my dataset has 34 colums). How do I sort of reset my fid value? also if anyone spots anything else wrong with the code that would be great. This is only a small portion of the code as I am just trying to get this part to work first.

close all
clear all
clc
fpath=uigetdir;
files=dir([fpath '\*.csv']);
files=char(files.name);
for n=1:size(files,1)
    fid=fopen([fpath '\' files(n,:)]);
    data{n}=textscan(fid, '%s %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f','Delimiter',',','CollectOutput',1, 'Headerlines',1);
    fclose(fid);
    data{1,n}{1,1}=datenum(data{1,n}{1,1},'dd-mmm-yyyy HH:MM:SS');
end

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Stephen23 on 25 Nov 2022

Edited: Stephen23 on 25 Nov 2022

Some tips on looping over filenames:

fpath = uigetdir;
files = dir(fullfile(fpath,'*.csv')); % use FULLFILE rather than text concatenation.
for n = 1:numel(files) % no need for a char array...
     fnm = fullfile(fpath,files(n).name); % ... you can access the structure directly.
     ...
     files(n).data  = ... optional, if you want to store any data
 end

As Image Analyst wrote in your other answer, you should not convert the filenames into a character array.

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Answer 1

Star Strider on 24 Nov 2022

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https://ch.mathworks.com/matlabcentral/answers/1862173-how-do-i-reset-a-fileid-value#answer_1111043

Using:

fclose('all')

should close all of them. You can then start with fid = 3.

Also, I lost count of the number of '%f' there are. You can avoid writing all that with:

['%s' repmat('%f', 1, 33)]
ans = '%s%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f%f'

And I don’t understand using datenum here:

data{1,n}{1,1}=datenum(data{1,n}{1,1},'dd-mmm-yyyy HH:MM:SS');

The datetime function allows for sorting, comparisons, logical operations, and a number of others.

.

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Star Strider on 25 Nov 2022

The readtable funciton imports the first column automatically as a datetime array, although it doesn’t have an associated 'TimeZone' property, so I set it to 'UTC'.

Assuming that ‘Hmax’ is the maximum wave height, I have no problems retrieving it and plotting it. (Plotting all of them reveals wave heights of 10000 meters, so I assumes that codes for missing data, since a wave height of that amplitude would be notable!)

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1207193/GdS_allwaveparameters2015.csv', 'VariableNamingRule','preserve')

T1 = 17520×34 table

Date/Time (GMT) Latitude Longitude Percentage of waves Hmax (m) Tmax (s) H1/10 (m) T1/10 (s) H1/3 (m) T1/3 (s) Hav Tav Eps Number of waves Tp (s) Direction (deg) Spread (deg) Tm02 (Tm)(s) Hm0 (Hs)(m) TI (s) T1 (s) Tc (s) Tdw2 (s) Tdw1 (s) Tpc (s) nu eps QP Ss Tref (deg C) SST (deg C) battery Te (s) P (kW/m2) ____________________ ________ _________ ___________________ ________ ________ _________ _________ ________ ________ _____ ___ _____ _______________ ______ _______________ ____________ ____________ ___________ ______ ______ ______ ________ ________ _______ _____ _____ ____ _____ ____________ ___________ _______ ______ _________ 01-Jan-2015 00:00:00 51.25 1.4832 100 1.46 4.7 1.07 4.5 0.87 4.5 0.55 3.8 0.515 469 5.6 184 10 4 0.99 4.9 4.3 3.1 4.5 5.7 5.7 0.356 0.642 2.49 0.04 9999 9999 9999 4.7 2.26 01-Jan-2015 00:30:00 51.25 1.4832 100 1.89 4.9 1.08 4.8 0.86 4.8 0.561 4.2 0.59 437 4.3 191 21 3.8 0.97 4.6 4 3 4.2 4.8 5.4 0.35 0.618 2.08 0.044 25.1 8.3 1 4.4 2.04 01-Jan-2015 01:00:00 51.25 1.4833 100 1.48 5.3 1.15 5.1 0.94 5.1 0.605 4.5 0.584 401 5.9 183 12 4.1 1.04 4.9 4.3 3.1 4.5 5.5 5.7 0.344 0.634 2.35 0.04 25.1 8.2 1 4.7 2.5 01-Jan-2015 01:30:00 51.25 1.4826 100 1.68 5.6 1.19 5.4 0.95 5.3 0.6 4.6 0.605 391 5.9 186 12 4.3 1.03 5.1 4.5 3.3 4.7 6 5.9 0.336 0.62 2.52 0.036 25.1 8.2 1 4.9 2.55 01-Jan-2015 02:00:00 51.25 1.4825 100 2.36 6 1.38 5.5 1.08 5.7 0.673 4.9 0.543 367 6.3 186 16 4.7 1.12 5.5 4.9 3.6 5.1 7.2 6.2 0.329 0.638 3.02 0.032 25.1 8.1 1 5.3 3.27 01-Jan-2015 02:30:00 51.25 1.4825 100 2.74 5.5 1.62 5.7 1.27 5.7 0.796 5 0.552 362 6.3 177 18 4.6 1.13 5.5 4.9 3.6 5.1 6.3 6.3 0.332 0.628 2.45 0.034 25.1 8.1 1 5.3 3.33 01-Jan-2015 03:00:00 51.25 1.4825 100 2.49 6.2 1.63 6.2 1.29 6.3 0.822 5.3 0.565 339 6.7 176 16 5 1.4 5.8 5.2 4 5.4 7.6 6.5 0.305 0.616 3.14 0.036 25.1 8 1 5.6 5.39 01-Jan-2015 03:30:00 51.25 1.4823 100 2.45 6.1 1.63 6.2 1.25 6.3 0.797 5.4 0.545 332 6.7 172 15 5.3 1.47 6.1 5.6 4.1 5.7 8.8 6.7 0.306 0.631 3.73 0.033 25.1 8 1 5.8 6.15 01-Jan-2015 04:00:00 51.25 1.4823 100 1.85 6.4 1.35 6.1 1.08 6.1 0.683 5.3 0.598 343 6.7 174 15 4.9 1.15 5.9 5.2 3.7 5.4 7.3 6.7 0.354 0.664 2.69 0.031 25.1 7.9 1 5.6 3.64 01-Jan-2015 04:30:00 51.249 1.4823 100 2.18 5.7 1.18 6 0.92 5.7 0.58 4.6 0.605 391 6.7 176 15 4.2 1.02 5.5 4.6 3.1 4.9 6.9 6.6 0.414 0.682 2.53 0.036 9999 9999 9999 5.2 2.66 01-Jan-2015 05:00:00 51.25 1.4823 100 1.44 5.9 1.11 5.6 0.93 5.6 0.59 4.5 0.631 402 6.7 176 14 4.1 0.96 5.5 4.5 2.8 4.9 7.3 6.7 0.464 0.726 2.78 0.037 9999 9999 9999 5.3 2.41 01-Jan-2015 05:30:00 51.25 1.4823 100 1.51 5.7 1.09 5.8 0.89 5.8 0.55 4.4 0.656 412 6.3 180 18 4.2 0.92 5.5 4.6 2.8 4.9 7.5 6.5 0.452 0.742 3.15 0.033 9999 9999 9999 5.2 2.17 01-Jan-2015 06:00:00 51.25 1.4824 100 1.89 5.9 1.18 5.7 0.94 5.7 0.59 4.7 0.68 385 6.3 188 20 4.4 1.45 5.3 4.7 3.2 5 7.1 6 0.37 0.69 3.17 0.047 9999 9999 9999 5.3 5.49 01-Jan-2015 06:30:00 51.25 1.4828 100 2.56 5.4 1.67 5.5 1.34 5.4 0.88 4.8 0.617 377 5.3 186 16 4 1.49 5 4.2 2.9 4.5 5.8 5.8 0.386 0.67 2.49 0.061 9999 9999 9999 4.8 5.25 01-Jan-2015 07:00:00 51.25 1.4828 100 2.48 4.9 1.68 5 1.3 5 0.82 4 0.583 446 5.9 188 24 3.8 1.43 4.8 4.1 2.9 4.3 5.4 5.7 0.382 0.648 2.2 0.062 9999 9999 9999 4.5 4.52 01-Jan-2015 07:30:00 51.25 1.4828 100 2.22 4.5 1.65 5 1.3 4.9 0.84 4 0.578 447 5.6 190 18 3.7 1.55 4.8 4 2.8 4.3 5.2 5.8 0.397 0.662 2.09 0.071 9999 9999 9999 4.6 5.45

VN = T1.Properties.VariableNames;

DT = T1.('Date/Time (GMT)')

DT = 17520×1 datetime array

01-Jan-2015 00:00:00 01-Jan-2015 00:30:00 01-Jan-2015 01:00:00 01-Jan-2015 01:30:00 01-Jan-2015 02:00:00 01-Jan-2015 02:30:00 01-Jan-2015 03:00:00 01-Jan-2015 03:30:00 01-Jan-2015 04:00:00 01-Jan-2015 04:30:00 01-Jan-2015 05:00:00 01-Jan-2015 05:30:00 01-Jan-2015 06:00:00 01-Jan-2015 06:30:00 01-Jan-2015 07:00:00 01-Jan-2015 07:30:00 01-Jan-2015 08:00:00 01-Jan-2015 08:30:00 01-Jan-2015 09:00:00 01-Jan-2015 09:30:00 01-Jan-2015 10:00:00 01-Jan-2015 10:30:00 01-Jan-2015 11:00:00 01-Jan-2015 11:30:00 01-Jan-2015 12:00:00 01-Jan-2015 12:30:00 01-Jan-2015 13:00:00 01-Jan-2015 13:30:00 01-Jan-2015 14:00:00 01-Jan-2015 14:30:00

T1.('Date/Time (GMT)').TimeZone = 'UTC'; % Set 'TimeZone' Property

T1.('Date/Time (GMT)').TimeZone % Check

ans = 'UTC'

figure

plot(T1.('Date/Time (GMT)'), T1.('Hmax (m)')) % Variable Name Reference

grid

xlim([0 hours(24)]+T1{1,1})

xlabel(VN{1})

ylabel(VN{5})

title('First 24 Hours Hmax')

figure

plot(T1{:,1}, T1{:,5}) % Column Index Reference

grid

xlim([0 hours(24)]+T1{1,1})

xlabel(VN{1})

ylabel(VN{5})

title('First 24 Hours Hmax')

This would likely require the Mapping Toolbox to plot with respect to the geographic coordinates. Since I don’t have it (and so have very little experience with it other than here on Answers), I defer to you for that.

.

Whale_Shark on 25 Nov 2022

Edited: Whale_Shark on 25 Nov 2022

Good person, it seems i require your assistance once again. So I was typing in the code line by line just to see if I typed it in correctly but now I get the error code:

Dot indexing is not supported for variables of this type.

Here is what I've typed in:

close all
 clear all
 clc
 
 %Load in the data
 fpath=uigetdir;
 files=dir([fpath '\*.csv']);
 files=char(files.name);
 %for loop to go through the variable files, creating variables for wave
 %height (Hmax [H])), max period (Tmax [T]), and geographical direction in
 %degrees (Directiondeg [direction]). Using textscan function to read the
 %data files.
 for n=1:size(files,1)
     fid=fopen([fpath '\' files(n,:)]);
     data{n}=textscan(fid, ['%s' repmat('%f', 1,34)],'Delimiter',',','CollectOutput',1, 'Headerlines',1);
     fclose(fid);
     %readmatrix to set datetime array for first column in the data.
     T1=readmatrix([fpath '\' files(n,:)]);
     VN=T1.Properties.VariableNames;
     DT=T1.('Date\Time (GMT)');
     T1.('Date\Time (GMT)').TimeZone='UTC';
     T1.('Date\Time (GMT)').TimeZone
 end

It produces T1 and the data is there, but the time column shows as NaN due to the dot indexing error.

Whale_Shark on 25 Nov 2022

Edited: Whale_Shark on 25 Nov 2022

So the readmatrix was me being an idiot and not realising that i had typed readmatrix instead of readtable. It now produces the variables with the headers VN and T1 with the data values (see imported picture below),

but produces a warning and anothe error (see imported picture below).

close all
 clear all
 clc
 
 %Load in the data
 fpath=uigetdir;
 files=dir([fpath '\*.csv']);
 files=char(files.name);
 %for loop to go through the variable files, creating variables for wave
 %height (Hmax [H])), max period (Tmax [T]), and geographical direction in
 %degrees (Directiondeg [direction]). Using textscan function to read the
 %data files.
 for n=1:size(files,1)
     fid=fopen([fpath '\' files(n,:)]);
     data{n}=textscan(fid, ['%s' repmat('%f', 1,34)],'Delimiter',',','CollectOutput',1, 'Headerlines',1);
     fclose(fid);
     %readtable to set datetime array for first column in the data.
     T1=readtable([fpath '\' files(n,:)]);
     VN=T1.Properties.VariableNames;
     DT=T1.('Date/Time (GMT)');
     T1.('Date/Time (GMT)').TimeZone='UTC';
     T1.('Date/Time (GMT)').TimeZone
 end
 