How can I load 100 files with similar names and/or string in just one step in MATLAB? - matlab

I have 100 ASCII files in my directory all named as follows:
int_001.ASC
int_002.ASC
int_003.ASC
.
.
.
int_099.ASC
int_100.ASC
I have to import them in MATLAB all with importdata, which should work as follows:
A = importdata('int_001.ASC', ' ', 9)
x = A.data(:,1)
y = A.data(:,2)
My question is: how can I avoid writing 100 times importdata? Is there a way to write the first string only and then have all data uploaded?
Thanks


fls = dir( 'int_*.ASC' );
for fi=1:numel(fls)
A{fi} = importdata( fls(fi).name, ' ', 9 );
% ...
end
UPDATE:
You may use string formatting to read the files according to their numbers:
for fi=1:100
A{fi} = importdata( sprintf('int_%03d.ASC', fi ), ' ', 9 );
% ...
end


You can use strcat function in a for loop :
for k=1:n
fileName = strcat('int_',num2str(k, '%03d'),'.ASC');
A(k) = importdata(fileName, ' ', 9);
x(k) = A(k).data(:,1);
y(k) = A(k).data(:,2);
end


If you want to take this a little overboard:
alldata = arrayfun(...
#(dirEntry)importdata(dirEntry.name, ' ', 9), ...
dir('int_*.ASC'),...
'uniformoutput',false);
This line does the following
Gets a listing of all files matching the partial filename, as an array of structures (h/t Shai)
For each element in that array, performs the importdata call from your original post.
Compiles all the outputs into a cell array.

Related

Matlab: Select a variable name and find the corresponding value

Can somebody explain me how i get some specific values after the = sign? The input File is a .subvar file format.
I dont know how to jump in the right row and column to get the value. Do you have a matlab tutorial link for such a problem.
I need for example two specific values (after the = sign):
The value of $_Wk1_lr_m and $_Wk1_voll_m
!file.version=1.543!
! Testautomatisch
subvargroup.begin ($G_Wk1)
subvar( $_Wk1_lr_C_x, str = ' 0.019 ' )
subvar( $_Wk1_lr_m, str = ' 15601 ' ) ! [kg] lr
subvar( $_Wk1_lr_C_y, str = '-0.007 ' )
subvar( $_Wk1_lr_C_z, str = ' 1.644 ' )
subvar( $_Wk1_voll_m, str = ' 33690 ' ) ! [kg] voll
subvargroup.end ($G_Wk1)
What are the first steps to get the right row and the right column? Thank you and stay at home :)

read the file line by line, match the line format and extract the values using regular expression regexp
fid=fopen('mydata.subvars','rt');
res=struct;
while(~feof(fid))
line=fgetl(fid);
if(regexp(line,'^\s*subvar\(','once'))
val=regexp(line,'\$_(\w+),\s*str\s*=\s*''\s*([0-9.-]+)\s*','tokens');
if(length([val{:}])==2)
res.(val{1}{1})=str2num(val{1}{2});
end
end
end
fclose(fid);
here is the result
>> res
res =
Wk1_lr_C_x: 0.0190
Wk1_lr_m: 15601
Wk1_lr_C_y: -0.0070
Wk1_lr_C_z: 1.6440
Wk1_voll_m: 33690

MATLAB - replace the string in a text file with index and delete those line without indexed

I have a text file with data structure like this
30,311.263671875,158.188034058,20.6887207031,17.4877929688,0.000297248129755,aeroplane
30,350.668334961,177.547393799,19.1939697266,18.3677368164,0.00026999923648,aeroplane
30,367.98135376,192.697219849,16.7747192383,23.0987548828,0.000186387239864,aeroplane
30,173.569274902,151.629364014,38.0069885254,37.5704650879,0.000172595537151,aeroplane
30,553.904602051,309.903320312,660.893981934,393.194030762,5.19620243722e-05,aeroplane
30,294.739196777,156.249740601,16.3522338867,19.8487548828,1.7795707663e-05,aeroplane
30,34.1946258545,63.4127349854,475.104492188,318.754821777,6.71026540999e-06,aeroplane
30,748.506652832,0.350944519043,59.9415283203,28.3256549835,3.52978979379e-06,aeroplane
30,498.747009277,14.3766479492,717.006652832,324.668731689,1.61551643174e-06,aeroplane
30,81.6389465332,498.784301758,430.23046875,210.294677734,4.16855394647e-07,aeroplane
30,251.932098389,216.641052246,19.8385009766,20.7131652832,3.52147743106,bicycle
30,237.536972046,226.656692505,24.0902862549,15.7586669922,1.8601918593,bicycle
30,529.673400879,322.511322021,25.1921386719,21.6920166016,0.751171214506,bicycle
30,255.900146484,196.583847046,17.1589355469,27.4430847168,0.268321367912,bicycle
30,177.663650513,114.458488464,18.7516174316,16.6759414673,0.233057001606,bicycle
30,436.679382324,273.383331299,17.4342041016,19.6081542969,0.128449092153,bicycle
I want to index those file with a label file.and the result will be something like this.
60,509.277435303,284.482452393,26.1684875488,31.7470092773,0.00807665128377,15
60,187.909835815,170.448471069,40.0388793945,58.8763122559,0.00763951029512,15
60,254.447280884,175.946624756,18.7212677002,21.9440612793,0.00442053096776,15
However there might be some class that is not in label class and I need to filter those line out so I can use load() to load in.(you can't have char inside that text file and execute load().
here is my implement:
function test(vName,meta)
f_dt = fopen([vName '.txt'],'r');
f_indexed = fopen([vName '_indexed.txt'], 'w');
lbls = loadlbl()
count = 1;
while(true),
if(f_dt == -1),
break;
end
dt = fgets(f_dt);
if(dt == -1),
break
else
dt_cls = strsplit(dt,','){7};
dt_cls = regexprep(dt_cls, '\s+', '');
cls_idx = find(strcmp(lbls,dt_cls));
if(~isempty(cls_idx))
dt = strrep(dt,dt_cls,int2str(cls_idx));
fprintf(f_indexed,dt);
end
end
end
fclose(f_indexed);
if(f_dt ~= -1),
fclose(f_dt);
end
end
However it work very very slow because the text file contains 100 thousand of lines. Is it anyway that I could do this task smarter and faster?

You may use textscan, and get the indices/ line numbers of the labels you want. After knowing the line numbers, you can extract what you want.
fid = fopen('data.txt') ;
S = textscan(fid,'%s','delimiter','\n') ;
S = S{1} ;
fclose(fid) ;
%% get bicycle lines
idx = strfind(S, 'bicycle');
idx = find(not(cellfun('isempty', idx)));
S_bicycle = S(idx)
%% write this to text file
fid2 = fopen('text.txt','wt') ;
fprintf(fid2,'%s\n',S_bicycle{:});
fclose(fid2) ;
From S_bicycle, you can extract your numbers.

MATLAB how to automatically read a number of files

I would like to plot a number of 3D graphs from different data files. For example I am using
fid = fopen('SS 1.dat','r');
to read the first file and then plot a graph. How to set the program to change the name to 'SS 2.dat' automatically? Also for the tenth file the name becomes 'SS 10.dat' which has one space less (i.e.only two space between SS and 10) then the first to ninth files. How to set the program to adjust for that? Thank you.

Use dir:
filenames = dir('*.dat'); %//gets all files ending on .dat in the pwd
for ii =1:length(filenames)
fopen(filenames(ii),'r');
%//Read all your things and store them here
end
The beauty of dir as opposed to the other solutions here is that you can get the contents of the pwd (present working directory) in one single line, regardless of how you called your files. This makes for easier loading of files, since you do not have any hassle with dynamic file names.

The following code displays a lazy way to print the names from 1 to 999 that you mentioned:
for ii=1:999
ns = numel(num2str(ii));
switch ns
case 1
fname = ['ss ' num2str(ii) '.dat'];
case 2
fname = ['ss ' num2str(ii) '.dat'];
case 3
fname = ['ss ' num2str(ii) '.dat'];
end
end
Another way:
is to use the backslash character in the formatting of the filename as follows:
fstr = 'ss ';
for ii = 1:999
ns = numel(num2str(ii));
for jj = 1:ns-1
fstr = [fstr '\b'];
end
ffstr = sprintf(fstr);
fname = [ffstr num2str(ii) '.dat'];
disp(fname);
end
there are many better ways to do this though

prefix = 'SS';
for n = 1:10
if n == 10
filename = [prefix ' ' num2str(n) '.dat'];
else
filename = [prefix ' ' num2str(n) '.dat'];
end
fid = fopen(filename, 'r');
...
end

Matlab) what should I put more with function for, sttrep, cell?

I want to make the results like this:
phraseblanks
phrasemat = Hello and how are you?
Hi there everyone!
How is it going?
WHazzup?
Phrase 1 had 4 blanks
Phrase 2 had 3 blanks
Phrase 3 had 2 blanks
Phrase 4 had 0 blanks
New phrasemat is :
Hello&and&how&are&you?
Hi&there&everyone!
How&is&it&going?
WHazzup?
so I made script "phraseblanks.m":
phrasemat = char('Hello and how are you?', ...
'Hi there everyone!', 'How is it going?', 'WHazzup?')
[r, c] = size(phrasemat);
for i = 1:r
phrasemat_new = cell(r, c);
howmany = countblanks(phrasemat(i, :));
fprintf('Phrase %d had %d blanks\n', i, howmany);
phrasemat(i,:) = strrep(phrasemat(i,:),' ','&')
phrasemat_new{i,:} = [phrasemat(i,:)];
end
fprintf('Changing one is %s\n', eval('phrasemat_new'));
script "countblanks.m":
function num = countblanks(phrase)
% countblanks returns the # of blanks in a trimmed string
% Format: countblanks(string)
num = length(strfind(strtrim(phrase), ' '));
end
and I keep having errors.
please help me..

I modified slightly your phraseblanks.m so that it works.
phrasemat = {'Hello and how are you?', ...
'Hi there everyone!', ...
'How is it going?', ...
'WHazzup?'};
r = numel(phrasemat);
phrasemat_new = cell(1, r);
for i = 1:r
howmany = countblanks(phrasemat{i});
fprintf('Phrase %d had %d blanks\n', i, howmany);
phrasemat{i} = strrep(phrasemat{i}, ' ', '&');
phrasemat_new(i) = phrasemat(i);
end
fprintf('Changing one is %s\n', phrasemat_new{:});
Obviously it could be written in a nicer, more "matlaby-way", but I didn't want to stride too far from your original version. Also you could consider using regular expressions, since if you have to spaces next to each other and you want to treat them as one blank space.

MATLAB: Get the last modification time of a file

I am looking for MATLAB code that does some routine (updates a file.m), if file.csv is edited more recently than file.m.
Something that should look like:
% Write time extraction
tempC = GetFileTime('file.csv', [], 'Write');
tempdateC = tempC.date
tempM = GetFileTime('file.m', [], 'Write');
tempdateM = tempM.date
% Write time comparison
if numel(dir('file.m')) == 0 || tempdateC >= tempdateM
matDef = regexprep(fileread('file.csv'), '(\r\n|\r|\n)', ';\n');
f = fopen('file.m', 'w');
fwrite(f, ['Variable = [' matDef(1:end) '];']);
fclose(f);
end
The lines for timestamp extraction seem to be incorrect MATLAB code. The rest works (Evaluate variables in external file strings).

You can extract the modification time of a file using MATLAB's dir command. Something like:
function modTime = GetFileTime(fileName)
listing = dir(fileName);
% check we got a single entry corresponding to the file
assert(numel(listing) == 1, 'No such file: %s', fileName);
modTime = listing.datenum;
end
Note that the output is in MATLAB's datenum serial date format.