I am trying to import some data from a .csv file, I have search for solutions but no one seems to solve my problem. My .csv is just one column of numbers, but when I try to read it with csvread('myfile.csv') it says that it cannot convert from string. When I double click on the .csv file in matlab I can see that every number from the .csv has this aspect:
"996.47"
So every number is between double commas, and whatever I do I can not get just the number between them. I am trying also opening the file and with textscan but I find no way. Thank you very much in advance.
You can try this workaround:
V = dlmread('myfile.csv','"');
v = V(:,2)
According to your description you have one column of values formatted like "996.47". The first line creates a matrix where columns are delimited by '"' - you get three columns where the middle one is filled with your values. The second line extracts the middle column.
what about using
importdata('yourfile.csv')
It should work if you are only interested in data.
If you want a more generic solution that doesn't need to deal with indexing, you can use MATLAB's built-in function importdata.
x = importdata('yourfile.csv'); % reads in the file as text surrounded by double quotes
x = cellfun(#str2num,strrep(v,'"','')); % removes the double quotes and changes text to numbers
Related
I have two .csv files which I am trying to read into Matlab as numeric matrices. Call it list_a, simply has two columns of ID numbers and corresponding values (appr. 50000 lines) with a ',' delimiter. list_b has 6 columns with a ';' delimiter. I am only interested in the first two columns containing containing numbers; the other columns contain text that I don't care about.
I initially tried using the readtable function in Matlab but noticed that these values aren't stored as numeric values, which is a requirement I have. I couldn't figure out how to cast these as integers after reading them either.
For list_a I have used the dlmread function, which I believes reads the file as numeric values.
For list_b I have tried using the dlmread function in which row and column offsets can be specified (https://www.mathworks.com/help/matlab/ref/dlmread.html#d117e329603) - the problem here is however, that the length of the file could change in the future, so I'm not sure what to enter for the row offsets.
I'm also not sure I understand how this function works, considering I tried testing it for the first 1000 rows as follows:
csv_matrix = dlmread(csv_fullpath,';',[1 1 1000 2]);
and subsequently got the following error message - even though "field number 3" shouldn't even be included in the first place:
Error using dlmread (line 147)
Mismatch between file and format character vector.
Trouble reading 'Numeric' field from file (row number 1, field number 3) ==>
RandomTextInFile\n Error in Damage_List_Reader (line 15)
csv_matrix = dlmread(csv_fullpath,';',[1 1 1000 3]);
I get the impression that I'm making this problem a lot harder than it needs to be so if there's an all around better way to do this, I'm all ears.. Thanks!
I would suggest using fopen in combination with textscan (e.g. for list_a) like this:
file = fopen('list_a.csv');
out = textscan(file, '%d%f', 'delimiter', ',');
ID = out{1};
Vals = out{2};
'%d%f' specifies the FormatSpec, so the way how the data is formatted in file. With this, you can capture any data from a csv file (and also omit data). I recommend reading the textscan Matlab doc for further formatting issues.
P.S.: I think you can put and "end" (without the quotations) instead of one of the row offset values if the number of rows/cols isn't fixed.
I'm writing a code to import data from a CSV file and convert it into an Octave matrix. The imported data can be seen in the following snap:
In the next step I added the following command to delete the commas and "":
meas_raw_temp = strrep(meas_raw_temp,',',' ')
And then I get the data format in the following form:
The problem is that Octave still sees the data as 1 single 1-dimensional array. i.e., when I use the size command I get a single number, i.e. 2647. What I need to have is a matrix output, with each line of the snaps being a row of the matrix, and with each element separated.
Any thoughts?
Here's what's happening.
You have a 1-dimensional (rows only) cell array. Each element (i.e. cell) in the cell array contains a single string.
Your strings contain commas and literal double-quotes in them. You have managed to get rid of them all by replacing them in-place with an 'empty string'. Good. However that doesn't change the fact that you still have a single string per cell.
You need to create a for loop to process each cell separately. For each cell, split the string into its components (i.e. 'tokens') using ' ' (i.e. space) as the delimiter. You can use either strsplit or strtok appropriately to achieve this. Note that the 'tokens' you get out of this process are still of 'string' type. If you want numbers, you'll need to convert them (e.g. using str2double or something equivalent).
For each cell you process, find a way to fill the corresponding row of a preallocated matrix.
As Adriaan has pointed out in the comments, the exact manner in which you follow the steps above programmatically can vary, therefore I'm not going to provide the range of possible ways that you could do so, and I'm limiting the answer to this question to the steps above, which is how you should think about solving your problem.
If you attempt these steps and get stuck on a 'programmatic' aspect of your implementation, feel free to ask another stackoverflow question.
I have been trying in vain for days to do one seemingly simple thing--I want to read data from a .txt file that looks like this:
0.221351321
0.151351321
0.235165165
8.2254546 E-7
into Matlab. I've been able to load the data in the .txt file as a column vector using the fscanf command, like so:
U=fscanf(FileID, '%e')
provided that I go through the file first and remove the space before the 'E' wherever scientific notation occurs in the data set.
Since I have to generate a large number of such sets, it would be impractical to have to do a search-and-replace for every .txt file.
Is there a way for matlab to read the data as it appears, as in the above example (with the space preceding 'E'), and put it into a column vector?
For anyone who knows PARI-GP, an alternate fix would be to have the output devoid of spaces in the first place--but so far I haven't found a way to erase the space before 'E' in scientific notation, and I can't predict if a number in scientific notation will appear or not in the data set.
Thank you!
Thank you all for your help, I have found a solution. There is a way to eliminate the space from PARI-GP, so that the output .txt file has no spaces to begin with. I had the output set to "prettymatrix". One needs to enter the following:
? \o{0}
to change the output to "Raw," which eliminates the space before the "E" in scientific notation.
Thanks again for your help.
A simple way, may not be the best, is to read line by line, remove the space and convert back to floating point number.
For example,
x = []
tline = fgetl(FileID);
while ischar(tline)
x = [x str2num(tline(find(~isspace(tline))))]
tline = fgetl(FileID);
end
One liner:
data = str2double(strsplit(strrep(fileread('filename.txt'),' ',''), '\n'));
strrep removes all the spaces, strsplit takes each line as a separate string, and str2double coverts the strings to numbers.
I have a fixed width file format (original was input for a Fortran routine). Several lines of the file look like the below:
1078.0711005.481 932.978 861.159 788.103 716.076
How this actually should read:
1078.071 1005.481 932.978 861.159 788.103 716.076
I have tried various methods, textscan, fgetl, fscanf etc, however the problem I have is, as seen above, sometimes because of the fixed width of the original files there is no whitespace between some of the numbers. I cant seem to find a way to read them directly and I cant change the original format.
The best I have come up with so far is to use fgetl which reads the whole line in, then I reshape the result into an 8,6 array
A=fgetl
A=reshape(A,8,6)
which generates the following result
11
009877
703681
852186
......
049110
787507
118936
So now I have the above and thought I might be able to concatenate the rows of that array together to form each number, although that is seeming difficult as well having tried strcat, vertcat etc.
All of that seems a long way round so was hoping for some better suggestions.
Thanks.
If you can rely on three decimal numbers you can use a simple regular expression to generate the missing blanks:
s = '1078.0711005.481 932.978 861.159 788.103 716.076';
s = regexprep(s, '(\.\d\d\d)', '$1 ');
c = textscan(s, '%f');
Now c{1} contains your numbers. This will also work if s is in fact the whole file instead of one line.
You haven't mentioned which class of output you needed, but I guess you need to read doubles from the file to do some calculations. I assume you are able to read your file since you have results of reshape() function already. However, using reshape() function will not be efficient for your case since your variables are not fixed sized (i.e 1078.071 and 932.978).
If I did't misunderstand your problem:
Your data is squashed in some parts (i.e 1078.0711005.481 instead
of 1078.071 1005.481).
Fractional part of variables have 3 digits.
First of all we need to get rid of spaces from the string array:
A = A(~ismember(A,' '));
Then using the information that fractional parts are 3 digits:
iter = length(strfind(A, '.'));
for k=1:iter
[stat,ind] = ismember('.', A);
B(k)=str2double(A(1:ind+3));
A = A(ind+4:end);
end
B will be an array of doubles as a result.
I want to have a look at a large matrix in MATLAB such that all columns are printed in one single line rather than spread out over several lines.
Is such thing possible? That would be great to know.
Try disp(matrixName(:)). The matrixName(:) command turns your matrix into a long vector in column-major order, so it basically just shows you the first column, followed by the second, the third, etc.
If that does not do the trick, you could look into the doprint command.
EDIT: You could also save the matrix to a text file and view the file. You do this like so:
fileID = fopen('C:/path/to/file/myMatrix.txt');
fprintf(fileID, formatString, myMat);
fclose(fileID);
fopen documentation
fprintf documentation
Additional information can be found here
The formatString variable in the above tells fprintf how the data should be displayed. If you have a really big matrix with tons of columns, where all of the values are floats, the easiest way to create this string is to use something like:
formatString = strcat(repmat('%f ', 1, size(myMat, 2)), '\n');
This will create a long string specifying that each element in your matrix is a float, and where it goes, and then cap it off with a line feed so that the next row of your matrix starts on the next line.
Suppress your original matrix with a semicolon and then use the "disp" command to show your matrix however you want.
for i = 1 : length(matrix(1,:))
disp(matrix(:,i))
end
Some "obvious" answers:
You can choose a smaller font - then more values will fit in a line
You can play with the format command to have less digits displayed
(my favourite) Use the variable viewer - via "open selection" or Ctrl-D when the name of a variable is highlighted. This will show your matrix in an excel-like table.