I have a cell array which contains some descriptions, namely my_des.
my_des = [{'FRD'} {'1'}; {'UNFRD'} {'2'}; {'OTH'} {'3'};];
I also have an approximately 5000x1 cell array. The elements in this array are either 'FRD', 'UNFRD' or 'OTH'.
What I want to do is replace these text values with the corresponding numeric values in my_des.
Currently my only idea (which I think isn't that great) is to loop through my_des and do a string replacement.
Example:
So say my current vector looks like this:
FRD
FRD
OTH
UNFRD
OTH
FRD
Then my desired output would be this:
1
1
3
2
3
1
The numbers come from the my_des array
Do you want to use the characters '1', '2', '3' or just the numbers 1, 2, 3? The distinction is the difference between a 1 line answer and a 2 line answer!
Based on your example, let's use the following data:
arr = {'FRD'; 'FRD'; 'OTH'; 'UNFRD'; 'OTH'; 'FRD'};
Get the row index within my_des of each element in arr, and use that to get the corresponding 2nd column values...
% If you just want the *number* then this is all you need
[~, idx] = ismember(arr, my_des);
% idx is the row within column 1 of my_des where the value in arr is found
% >> idx = [1; 1; 3; 2; 3; 1]
% If you want to get the values my_des then use idx as a row index
out = mydes(idx, 2);
% out is the corresponding values from the 2nd column of my_des, whatever they may be.
% >> out = {'1'; '1'; '3'; '2'; '3'; '1'};
Aside: why are you declaring a cell array by concatenating 1-element cell arrays for my_des? Instead, you can just do this:
my_des = {'FRD', '1';
'UNFRD', '2';
'OTH', '3'};
Related
I Have a 8x18 structure with each cel containing a column vector of occurrences of a single event. I want to obtain data from some of these fields concatenated in a single array, without having to loop through it. I can't seem to find a way to vertically concatenate the fields I am interested in in a single array.
As an example I create the following structure with between 1 and 5 occurrences per cell:
s(62).vector(8,18).heading.occurrences=[1;2;3];
for i=1:62
for j=1:8
for k=1:18
y=ceil(rand(1)*5);
s(i).vector(j,k).heading.occurrences=rand(y,1);
end
end
end
Now if want to obtain all occurrences in several cells while keeping i constant at for instant i=1 the following works:
ss=s(1).vector([1 26 45]);
h=[ss.heading];
cell2mat({h.occurrences}')
Now I would want to do the same for s, for instance s([1 2 3]).vector([1 26 45]), how would that work? I have tried xx=s([1 2 3]), yy=xx.vector([1 26 45]) but this however yields the error:
Expected one output from a curly brace or dot indexing expression, but there were 3 results.
Is this also possible with a vector operation?
Here's a vectorized solution that accommodates using index vectors for s and the field vector:
sIndex = [1 2 3]; % Indices for s
vIndex = [1 26 45]; % Indices for 'vector' field
v = reshape(cat(3, s(sIndex).vector), 144, []);
h = [v(vIndex, :).heading];
out = vertcat(h.occurrences);
It uses cat to concatenate all the vector fields into an 8-by-18-by-numel(sIndex) matrix, reshapes that into a 144-by-numel(sIndex) matrix, then indexes the rows specified by vIndex and collects their heading and occurrences fields, using vertcat instead of cell2mat.
It's difficult to vectorize the entire operation, but this should work.
% get vector field and store in cell array
s_new = { s(1:3).vector };
% now extract heading field, this is a cell-of-cells
s_new_heading = cellfun(#(x) { x.heading }', s_new, 'UniformOutput', false);
occurences = {};
for iCell = 1:length(s_new_heading)
% use current cell
cellHere = s_new_heading{iCell};
% retain indices of interest, these could be different for each cell
cellHere = cellHere([ 1 26 45 ]);
% extract occurrences
h = cellfun(#(x) x.occurrences, cellHere, 'UniformOutput', false);
h_mat = cell2mat(h);
% save them in cell array
occurences = cat(1, occurences, h_mat);
end
I have a structure 1x300 called struct with 3 fields but I'm using only the third field called way. This field is, for each 300 lines, a vertor of index.
Here an exemple with 3 lines to explain my problem : I woud like to search if the last index of the first line is present in an other vector (line) of the field way.
way
[491751 491750 491749 492772 493795 494819 495843 496867]
[491753 491754 491755 491756]
[492776 493800 494823 495847 496867]
I tried with intersect function :
Inter=intersect(struct(1).way(end), struct.way);
but Matlab returns me an error :
Error using intersect (line 80)
Too many input arguments.
Error in file2 (line 9)
Inter=intersect(struct(1).way(end), struct.way);
I don't understand why I have this error. Any explanations and/or other(s) solution(s)?
Let the data be defined as
st(1).way = [491751 491750 491749 492772 493795 494819 495843 496867];
st(2).way = [491753 491754 491755 491756];
st(3).way = [492776 493800 494823 495847 496867]; % define the data
sought = st(1).way(end);
If you want to know which vectors contain the desired value: pack all vectors into a cell array and pass that to cellfun with an anonymous function as follows:
ind = cellfun(#(x) ismember(sought, x), {st.way});
This gives:
ind =
1×3 logical array
1 0 1
If you want to know for each vector the indices of the matching: modify the anonymous function to output a cell with the indices:
ind = cellfun(#(x) {find(x==sought)}, {st.way});
or equivalently
ind = cellfun(#(x) find(x==sought), {st.way}, 'UniformOutput', false);
The result is:
ind =
1×3 cell array
[8] [1×0 double] [5]
Or, to exclude the reference vector:
n = 1; % index of vector whose final element is sought
ind = cellfun(#(x) {find(x==st(n).way(end))}, {st([1:n-1 n+1:end]).way});
You propbably want to use ismember.
Consider what you are passing to the intersect/ismember functions too, struct.way isn't a valid argument, you may need to loop to iterate over each line of your struct (in this case it would be easier to have a cell array, or matrix with equal length rows).
output = zeros(300);
for ii = 1:300
for jj = 1:300
if ii ~= jj && ismember(struct(ii).way(end), struct(jj).way)
output(ii,jj) = 1;
end
end
end
Now you have a matrix output where the elements which are 1 identify a match between the last element in way in the struct row ii and the vector struct(jj).way, where ii are the matrix row numbers and jj the column numbers.
I have the following code:
L_sum = zeros(height(ABC),1);
for i = 1:height(ABC)
L_sum(i) = sum(ABC{i, ABC.L(i,4:281)});
end
Here my table:
Problem: My sum function sums the entire row values (col. 4-281) per date whereas I only want those cells to be added whose headers are in the cell array of ABC.L, for any given date.
X = ABC.L{1, 1}; gives (excerpt):
Red arrow: what sum function is referencing (L of same date).
Green arrow: what I am trying to reference now (L of previous date).
Thanks for your help
In general, in matlab you dont need to use for loops to do simple operations like selective sums.
Example:
Data=...
[1 2 3;
4 5 6;
7 8 9;
7 7 7];
NofRows=size(Data,1);
RowsToSum=3:NofRows;
ColToSum=[1,3];
% sum second dimension 2d array
Result=sum(Data(RowsToSum,ColToSum), 2)
% table mode
DataTable=array2table(Data);
Result2=sum(DataTable{RowsToSum,ColToSum}, 2)
To do that you need to first extract the columns you want to sum, and then sum them:
% some arbitrary data:
ABC = table;
ABC.L{1,1} = {'aa','cc'};
ABC.L{2,1} = {'aa','b'};
ABC.L{3,1} = {'aa','d'};
ABC.L{4,1} = {'b','d'};
ABC{1:4,2:5} = magic(4);
ABC.Properties.VariableNames(2:5) = {'aa','b','cc','d'}
% summing the correct columns:
L_sum = zeros(height(ABC),1);
col_names = ABC.Properties.VariableNames; % just to make things shorter
for k = 1:height(ABC)
% the following 'cellfun' compares each column to the values in ABC.L{k},
% and returns a cell array of the result for each of them, then
% 'cell2mat' converts it to logical array, and 'any' combines the
% results for all elements in ABC.L{k} to one logical vector:
col_to_sum = any(cell2mat(...
cellfun(#(x) strcmp(col_names,x),ABC.L{k},...
'UniformOutput', false).'),1);
% then a logical indexing is used to define the columns for summation:
L_sum(k) = sum(ABC{k,col_to_sum});
end
I have one big cell with N by 1 dimension. Each row is either a string or a double. A string is a variable name and the sequential doubles are its values until the next string (another variable name). For example:
data = {
var_name1;
val1;
val2;
val3;
val4;
val5;
var_name2;
val1;
val2;
var_name3;
val1;
val2;
val3;
val4;
val5;
val6;
val7}
and so on. I want to separate the data cell into three cells; {var_name and it's 5 values}, {var_name and it's 2 values}, {var_name and it's 7 values}. I try not to loop as much as possible and have found that vectorization along with cellfun works really well. Is it possible? The data cell has close to million rows.
I believe the following should do what you're after. The main pieces are to use cumsum to work out which name each row corresponds to, and then accumarray to build up lists per name.
% Make some data
data = {'a'; 1; 2; 3;
'b'; 4; 5;
'c'; 6; 7; 8; 9;
'd';
'e'; 10; 11; 12};
% Which elements are the names?
isName = cellfun(#ischar, data);
% Use CUMSUM to work out for each row, which name it corresponds to
whichName = cumsum(isName);
% Pick out only the values from 'data', and filter 'whichName'
% for just the values
justVals = data(~isName);
whichName = whichName(~isName);
% Use ACCUMARRAY to build up lists per name. Note that the function
% used by ACCUMARRAY must return something scalar from a column of
% values, so we return a scalar cell containing a row-vector
% of those values
listPerName = accumarray(whichName, cell2mat(justVals), [], #(x) {x.'});
% All that remains is to prepend the name to each cell. This ends
% up with each row of output being a cell like {'a', [1 2 3]}.
% It's simple to make the output be {'a', 1, 2, 3} by adding
% a call to NUM2CELL on 'v' in the anonymous function.
nameAndVals = cellfun(#(n, v) [{n}, v], data(isName), listPerName, ...
'UniformOutput', false);
cellfun is for applying a function to each element of a cell.
When you pass multiple arguments to cellfun like that, it takes the ith argument of data, indx_first, and indx_last, and uses each of them in the anonymous function. Substituting those variables in, your function evaluates to x(y : z), for each element x in data. In other words, you're doing data{i}(y : z), i.e., indexing the actual elements of the cell array, rather than indexing the cell array itself. I don't think that's what you want. Really you want data{y : z}, for each (y, z) pair given by corresponding elements in indx_first and indx_last, right?
If that's indeed the case, I don't see a vectorized way to solve your problem, because each of the "variables" has different size. But you do know how many variables you have, which is the size of indx_first. So I'd pre-allocate and then loop, like so:
>> vars = cell(length(indx_first), 2);
>> for i = 1:length(vars)
vars{i, 1} = data{indx_first(i) - 1}; % store variable name in first column
vars{i, 2} = [data{indx_first(i) : indx_last(i)}]; % store data in last column
end
At the end of this, you'll have a cell array with 2 columns. The first column in each row is the name of the variable. The second is the actual data. I.e.
{'var_name1', [val1 val2 val3 val4 val5];
'var_name2', [val1 val2];
.
.
.
I am having trouble converting a character variable to a number in Matlab.
Each cell in the char variable contains one of two possible words. I need to convert word_one (for example) to represent '1', and word_two to represent '2'.
Is there a command that will let me do this?
So far I've tried:
%First I converted 'Word' from cell to char
Word = char(Word);
Word(Word == 'Word_one') = '1';
Word(Word == 'Word_two') = '2';
However, I get the:
Error using ==
Matrix dimensions must agree.
When I try to include the first letter only (ie. 'W'), it only changes the first letter in the full word (ie. 1ord_one).
Is there an easy way to do this?
Thanks for your help - any advice is much appreciated!
Use ismember:
possibleWords = {'Word_one', 'Word_two'}; %// template: words corresponding to 1, 2, ...
words = {'Word_two', 'Word_one', 'Word_two'}; %// data: words you need to convert
[~, result] = ismember(words, possibleWords);
In this example,
result =
2 1 2
If you need more flexibility, you can specify the value corresponding to each word:
possibleWords = {'Word_one', 'Word_two'}; %// template: words corresponding to 1, 2, ...
correspondingValues = [1.1, 2.2]; %// template: value corresponding to each word
words = {'Word_two', 'Word_one', 'Word_two'}; %// data: words you need to convert
[~, ind] = ismember(words, possibleWords);
result = correspondingValues(ind);
which gives
result =
2.2000 1.1000 2.2000
Looks like there are a couple of potential issues here.
Use strcmp() (string compare) in place of your current equivalence statement. Comparing strings using == compares element by element and returns a logical vector (where here you want a single logical value). String comparison, strcmp(), will compare the entire strings instead and return a single value.
It's also probably not necessary for you to convert your cell array. You can maintain the cell array structure and address each cell individually.
Try something along the lines of the following snippet.
for i = 1:length(Word)
if strcmp(Word{i},'Word_one')
Word{i} = '1';
elseif strcmp(Word{i},'Word_two')
Word{i} = '2';
end
end
There are a number of ways to solve this problem. Here's my approach.
% define your words
words = {'word_one','word_two','word_two','word_one','word_one'};
% define a function to get the indexes of the words of interest
getindex = #(c, y) cellfun(#(x) strcmp(x,y), c);
% replace 'word_one' with '1'
words(getindex(words, 'word_one'))={'1'};
% replace 'word_two' with '2'
words(getindex(words, 'word_two'))={'2'};
words =
'1' '2' '2' '1' '1'
You can use short n simple unique -
input_cellarr = {'Word_two','Word_one','Word_two','Word_two','Word_one','Word_one'}
[~,~,out] = unique(input_cellarr)
Sample run -
input_cellarr =
'Word_two' 'Word_one' 'Word_two' 'Word_two' 'Word_one' 'Word_one'
out =
2
1
2
2
1
1
Explanation: unique works here because it will produce an ascending order sorted array with numeric arrays. Now, when used on cell arrays, that ascending order translates to alphabetical order sorting. Thus, unique(input_cellarr) would always have {'Word_one' , 'Word_two'} because one is alphabetically higher up than two. Therefore the out indices would always have the first unique ID as 1 for 'Word_one' and the second ID as 2 for 'Word_two'.