I have a table named cellName of size 10000*1. Each entry is a character string of cell names. Each cell name is of different length.
And I want to coerce it into a vector with 10000 elements. How can i do that in matlab? It should be very easy as that in r but i didn't find such command in matlab.
OR: I used readtable to load the 10000*1 table from csv file at the very beginning. It would be great if I can directly read the 10000*1 entries as a single vector too. This is what i did at first.
cellName = readtable('cell.csv');
cellName=cellName(1:10000,1);
Thank you in advance!
Clear example: A is a table of 5*1.
A= apple
banana
pear
peach
watermelon
And i want to coerce A into a vector of 5 elements: A=[apple,banana,pear,peach,watermelon] instead of a table
If a character cell array is what you want, I may have your answer. I also suggest you to read how to access data in a table.
readtable returns a Matlab table data type when succeeded. The table can be accessed like struct with your column name as the fieldname, or be indexed by {} operator like you would access a cell array.
In your example, assuming A is the return value of readtable and your
A = table({'apple','banana','pear','peach','watermelon'}','variableNames',{'cellName'})
Then you can either call
cellName = A.cellName
or
cellName = A{:,1}
to get your cell array.
Related
I have an excel file that I grab by:
ds = dataset('XLSFile',fullfile('file path here', 'waterReal.xlsx'))
It looks like this:
I want each column in its own numeric array though! Like how when I load an example dataset: load carsmall, I get a bunch of individual numeric arrays. But I can't figure out how to do that.
I can do this individually by writing:
A = ds.TEMP, B = ds.PROD, ...
Bu what if I had BIG excel file? What then?
You can convert a dataset to a struct or a cell like this:
To struct:
s = dataset2struct(ds, 'AsScalar',true)
To cell:
fnames = fieldnames(ds);
c = cell(1, numel(fnames));
for i = 1:numel(fnames)
c{i} = ds.(fnames{i});
end
By the way: use tables instead of datasets. They're newer and better. Use the readtable function to read your Excel file into a table. And tables are nicer enough that you might not want to bother converting them into a simpler cell array, because you can just grab the columns out with t{:,i} where t is your table and i is the index of the column you want.
I have a struct in MATLAB with the size 46x6, the fields are:
name, folder, date, bytes, isdir, datenum
Now I want all 46 entries of name. However, the MATLAB function getfield(structname, 'name') only returns the first entry.
How can I get all elements of the struct?
Name holds strings
If you want the results as a cell array you can call {structname(:).name}.
To return an array you can call [structname(:).name].
First I had to convert the Struct to a cell, and then access it with round brackets
tmp = struct2cell(mystruct)
tmp(1,:)
for i = 1:numel(structname)
name(i)= structname(i).name;
end
I have a dataset that I would like to categorise and store in a structure based on the value in one column of the dataset. For example, the data can be categorised into element 'label_100', 'label_200' or 'label_300' as I attempt below:
%The labels I would like are based on the dataset
example_data = [repmat(100,1,100),repmat(200,1,100),repmat(300,1,100)];
data_names = unique(example_data);
%create a cell array of strings for the structure fieldnames
for i = 1:length(data_names)
cell_data_names{i}=sprintf('label_%d', data_names(i));
end
%create a cell array of data (just 0's for now)
others = num2cell(zeros(size(cell_data_names)));
%try and create the structure
data = struct(cell_data_names{:},others{:})
This fails and I get the following error message:
"Error using struct
Field names must be strings."
(Also, is there a more direct method to achieve what I am trying to do above?)
According to the documentation of struct,
S = struct('field1',VALUES1,'field2',VALUES2,...) creates a
structure array with the specified fields and values.
So you need to have each value right after its field name. The way you are calling struct now is
S = struct('field1','field2',VALUES1,VALUES2,...)
instead of the correct
S = struct('field1',VALUES1,'field2',VALUES2,...).
You can solve that by concatenating cell_data_names and others vertically and then using {:} to produce a comma-separated list. This will give the cells' contents in column-major order, so each field name fill be immediately followed by the corresponding value:
cell_data_names_others = [cell_data_names; others]
data = struct(cell_data_names_others{:})
I'm a bit new to the matlab world, and I'm running into an issue that I'm sure has an easy solution.
I've imported some data from a text file and parsed out the headers, which resulted in a 1x35 cell called Data. In each cell (for example Data{1,1,1}) is data that looks like:
'600000 -947.772827 -107.045776 -70.818062'
'600001 -920.431396 -86.098122 -56.485119'
'600002 -878.332886 -88.673630 -85.249130'
'600003 -851.637695 -68.546539 -96.691711'
'600004 -834.707642 -28.951260 -73.218872'
'600005 -783.431580 40.657402 24.242268'
The problem is, each line is contained in a single column. I'd like to parse it out so that I have 4 columns instead of one.
I tried parsing out the Data cell even further using:
textscan(Data{1,1,1}, '%u%f10%f10%f10', 1)
But it resulted in the following error:
Error using textscan
First input must be of type double or string.
Can I use textscan this way, or do I need to use some other method to break out the text?
With textscan, you can only specify a single string or a single number. With your input, I suspect it is a 6 x 1 cell array of strings. As such, you have no choice but to iterate over each cell and convert each cell array contents with textscan Also, get rid of the %10 spacing as it's actually screwing up where you're parsing out the string. Also, set the identifier to identify the first number you see to double (%f) as opposed to unsigned integer (%u) to allow for easier conversion.
Therefore, do something like this:
>> Data{1,1,1} = {'600000 -947.772827 -107.045776 -70.818062'
'600001 -920.431396 -86.098122 -56.485119'
'600002 -878.332886 -88.673630 -85.249130'
'600003 -851.637695 -68.546539 -96.691711'
'600004 -834.707642 -28.951260 -73.218872'
'600005 -783.431580 40.657402 24.242268'};
>> format long g;
>> vals = cell2mat(cellfun(#(x) cell2mat(textscan(x, '%f%f%f%f', 1)), Data{1,1,1}, 'uni', 0))
vals =
Columns 1 through 3
600000 -947.772827 -107.045776
600001 -920.431396 -86.098122
600002 -878.332886 -88.67363
600003 -851.637695 -68.546539
600004 -834.707642 -28.95126
600005 -783.43158 40.657402
Column 4
-70.818062
-56.485119
-85.24913
-96.691711
-73.218872
24.242268
That statement vals = ... is quite a mouthful, but easy to explain. Start with this statement:
cell2mat(textscan(x, '%f%f%f%f', 1))
For a given cell x in Data{1,1,1}, we want to parse out four numbers for each string that is stored in x. textscan will place these numbers as individual cell elements into a cell array. We want to convert each element into a numeric array, and so cell2mat is required for us to do so.
In order to operate over all of the elements in Data{1,1,1}, we need to use cellfun to allow us to do so:
cellfun(#(x) cell2mat(textscan(x, '%f%f%f%f', 1)), Data{1,1,1}, 'uni', 0)
The first input is a function that operates on each cell stored in Data{1,1,1} (the second input). We are basically telling cellfun that we want to operate on each cell in the cell array stored in Data{1,1,1} in the way I talked about before. This function has input parameter x, which is one cell from Data{1,1,1}. Now, the uni flag is set to 0 because the output of cellfun will not be a single number, but an array of numbers - one array per line that you have in your cell array. The output of this stage would be a 6 element cell array where each location is a 4 element numeric array. To finish it off, we call cell2mat on this output to finally convert our text into a 2D matrix and therefore:
vals = cell2mat(cellfun(#(x) cell2mat(textscan(x, '%f%f%f%f', 1)), Data{1,1,1}, 'uni', 0))
format long g allows for better display formatting so we can see both the dominant number as well as the floating point numbers neatly.
I have a cell array that is a list of file names. I transposed them because I find that easier to work with. Now I am attempting to go through each line in each cell and remove the lines based on their file extension. Eventually, I want to use this list as file names to import data from. This is how I transpose the list
for i = 1:numel(F);
a = F(1,i);
b{i} = [a{:}'];
end;
The code I am using to try and read the data in each cell keeps giving me the error input must be of type double or string. Any ideas?
for i = 1:numel(b);
for k = 1:numel(b{1,i});
b(cellfun(textscan(b{1,i}(k,1),'%s.lbl',numel(b)),b))=[];
end;
end;
Thanks in advance.
EDIT: This is for MATLAB. Should have been clear on that. Thanks Brian.
EDIT2: whos for F is
Name Size Bytes Class Attributes
b 1x11 13986188 cell
while for a is
Name Size Bytes Class Attributes
a 1x1 118408 cell
From your description I am not certain how your F array looks, but assuming
F = {'file1.ext1', 'file2.ext2', 'file3.ext2', 'file2.ext1'};
you could remove all files ending with .ext2 like this:
F = F(cellfun('isempty', regexpi(F, '\.ext2$')));
regexpi, which operates on each element in the cell array, returns [] for all files not matching the expression. The cellfun call converts the cell array to a logical array with false at positions corresponding to files ending with .ext2and true for all others. The resulting array may be used as a logical index to F that returns the files that should be kept.
You're using cellfun wrong. It's signature is [A1,...,Am] = cellfun(func,C1,...,Cn). It takes a function as first argument, but you're passing it the result of textscan, which is a cell array of the matching strings. The second argument is a cell array as it should be, but it doesn't make sense to call it over and over in a loop. `cellfun´'s job is to write the loop for you when you want to do the same thing to every cell in a cell array.
Instead of parsing the filename yourself with textscan, I suggest you use fileparts
Since you're already looping over the cell array in transpose-step, it might make sense to do the filtering there. It might look something like this:
for i = 1:numel(F);
a = F(1,i);
[~,~,ext] = fileparts(a{:});
if strcmpi(ext, '.lbl')
b{i} = [a{:}'];
end
end;