I want to create a binary number in matlab and am having difficulty concatenating the numbers.
Here's what I tried so far:
testarray = zeros(10,10)
testarray = num2str(testarray) % Convert all values to type string
testarray(1,1) = num2str(1); % Fill with abitrary value
testarray(1,1) = strcat(testarray(1,1), num2str(0)); % Trying to make '10' here but instead I get this error: "Assignment has more non-singleton rhs dimensions than non-singleton subscripts"
Any help would be appreciated.
In your example, the problem is that '10' has size [1,2], but testarray(1,1) has size [1,1]. So you might consider using cells instead:
testarray = cell(5,5);
testarray{1,1} = strcat(testarray(1,1), num2str(0));
By the way, you should have a look at the function dec2bin.
From the documentation:
dec2bin(23)
ans =
10111
The resulting value is a string.
So if you want to concatenate two binary values (encoded as strings), just do:
['10' '11']
ans =
1011
Related
Given question - Given a list of 10 numbers, find the average of all such numbers which is a multiple of 3
num = []
newlist = []
for i in range(1, 11):
num.append(input())
for i in num:
if i%3==0:
newlist.append(i)
length = len(newlist)
total = sum(newlist)
average = total/length
print(average)
Getting this type error below at line 9 i.e. if i%3==0
not all arguments converted during string formatting
input() returns a string, so i%3 will actually perform printf-style string formatting. Since your input doesn't have any formatting specifiers, but the % operator's right operand is not empty, you get the error, because you attempted to format a sting that doesn't have enough formatting specifiers.
To solve this, convert your input to integers:
num.append(int(input()))
When you num.append(input()), the value of input() is a string. You need to first convert that to an int and handle any possible errors before continuing. One way to do this is to change it to:
num.append(int(input()))
Since all the values in num are strings, i % 3 tries to perform old-string formatting, which is not what you expect.
I have two lists of strings as a column in a table (PM25_spr{i}.MonitorID and O3_spr{i}.MonitorID). The lists are of different lengths. I want to compare the first 11 characters of each entry and pull out the index for each list where they are the same.
Example
List 1:
'01-003-0010-44201'
'01-027-0001-44201'
'01-051-0001-44201'
'01-073-0023-44201'
'01-073-1003-44201'
'01-073-1005-44201'
'01-073-1009-44201'
'01-073-1010-44201'
'01-073-2006-44201'
'01-073-5002-44201'
'01-073-5003-44201'
'01-073-6002-44201'
List 2:
'01-073-0023-88101'
'01-073-2003-88101'
'04-013-0019-88101'
'04-013-9992-88101'
'04-013-9997-88101'
'05-119-0007-88101'
'05-119-1008-88101'
'06-019-0008-88101'
'06-029-0014-88101'
'06-037-0002-88101'
'06-037-1103-88101'
'06-037-4002-88101'
'06-059-0001-88101'
'06-065-8001-88101'
'06-067-0010-88101'
'06-073-0003-88101'
'06-073-1002-88101'
'06-073-1007-88101'
'08-001-0006-88101'
'08-031-0002-88101'
I tried intersect, which isn't the right approach for what I want to do. I'm not sure how to use ismember given that I only want to look at the first 11 characters.
I tried strncmp, but Inputs must be the same size or either one can be a scalar.
chars2compare = length('18-097-0083');
strncmp(O3_spr{i}.MonitorID, PM25_spr{i}.MonitorID,chars2compare)
PM25_spr_MID = cell(length(years),1); % Preallocate cell array
for n = 1:length(PM25_spr{i}.MonitorID)
s = char(PM25_spr{i}.MonitorID(n)); % Convert string to char
PM25_spr_MID{i}(n) = cellstr(s(1:11)); % Pull out 1-11 characters and convert to cell
end
O3_spr_MID = cell(length(years),1); % Preallocate cell array
for n = 1:length(O3_spr{i}.MonitorID)
s = char(O3_spr{i}.MonitorID(n));
O3_spr_MID{i}(n) = cellstr(s(1:11));
end
[C, ia, ib] = intersect(O3_spr_MID{i}, PM25_spr_MID{i})
PerCap_spr_O3{i} = O3_spr{i}(ia,:);
PerCap_spr_PM25{i} = PM25_spr{i}(ib,:);
Assuming list1 and list2 to be the two input cell arrays, you can use few approaches.
I. Operate on cell arrays
With intersect -
%// Clip off after first 11 characters in each cell of the input cell arrays
list1_f11 = arrayfun(#(n) list1{n}(1:11),1:numel(list1),'uni',0)
list2_f11 = arrayfun(#(n) list2{n}(1:11),1:numel(list2),'uni',0)
%// Use intersect to find common indices in the input cell arrays
[~,idx_list1,idx_list2] = intersect(list1_f11,list2_f11)
With ismember -
%// Clip off after first 11 characters in each cell of the input cell arrays
list1_f11 = arrayfun(#(n) list1{n}(1:11),1:numel(list1),'uni',0)
list2_f11 = arrayfun(#(n) list2{n}(1:11),1:numel(list2),'uni',0)
%// Use ismember to find common indices in the input cell arrays
[LocA,LocB] = ismember(list1_f11,list2_f11);
idx_list1 = find(LocA)
idx_list2 = LocB(LocA)
II. Operate on char arrays
We can use char dierctly on the input cell arrays to get 2D char arrays as working with them could be faster than working withcells.
With intersect + 'rows' -
%// Convert to char arrays
list1c = char(list1)
list2c = char(list2)
%// Clip char arrays after first 11 columns
list1c_f11 = list1c(:,1:11)
list2c_f11 = list2c(:,1:11)
%// Use intersect with 'rows' option
[~,idx_list1,idx_list2] = intersect(list1c_f11,list2c_f11,'rows')
III. Operate on numeric arrays
We can convert the char arrays further to numeric arrays with just one column as that could lead to faster solutions.
%// Convert to char arrays
list1c = char(list1)
list2c = char(list2)
%// Clip char arrays after first 11 columns
list1c_f11 = list1c(:,1:11)
list2c_f11 = list2c(:,1:11)
%// Remove char columns of hyphens (3 and 7 for the given input)
list1c_f11(:,[3 7])=[];
list2c_f11(:,[3 7])=[];
%// Convert char arrays to numeric arrays
ncols = size(list1c_f11,2);
list1c_f11num = (list1c_f11 - '0')*(10.^(ncols-1:-1:0))'
list2c_f11num = (list2c_f11 - '0')*(10.^(ncols-1:-1:0))'
This point onwards you have three more approaches to work with that are listed next.
With ismember ( would be memory efficient, but maybe not fast across all datasizes) -
[LocA,LocB] = ismember(list1c_f11num,list2c_f11num);
idx_list1 = find(LocA)
idx_list2 = LocB(LocA)
With intersect (could be slow) -
[~,idx_list1,idx_list2] = intersect(list1c_f11num,list2c_f11num)
With bsxfun ( would be memory inefficient, but maybe fast for small to decent sized inputs) -
[idx_list1,idx_list2] = find(bsxfun(#eq,list1c_f11num,list2c_f11num'))
I have an cell array composed by several strings
names = {'2name_19surn', '3name_2surn', '1name_2surn', '10name_1surn'}
and I would like to sort them according to the prefixnumber.
I tried
[~,index] = sortrows(names.');
sorted_names = names(index);
but I get
sorted_names = {'10name_1surn', '1name_2surn', '2name_19surn', '3name_2surn'}
instead of the desired
sorted_names = {'1name_2surn', '2name_19surn', '3name_2surn','10name_1surn'}
any suggestion?
Simple approach using regular expressions:
r = regexp(names,'^\d+','match'); %// get prefixes
[~, ind] = sort(cellfun(#(c) str2num(c{1}), r)); %// convert to numbers and sort
sorted_names = names(ind); %// use index to build result
As long as speed is not a concern you can loop through all strings and save the first digets in an array. Subsequently sort the array as usual...
names = {'2name_2', '3name', '1name', '10name'}
number_in_string = zeros(1,length(names));
% Read numbers from the strings
for ii = 1:length(names)
number_in_string(ii) = sscanf(names{ii}, '%i');
end
% Sort names using number_in_string
[sorted, idx] = sort(number_in_string)
sorted_names = names(idx)
Take the file sort_nat from here
Then
names = {'2name', '3name', '1name', '10name'}
sort_nat(names)
returns
sorted_names = {'1name', '2name', '3name','10name'}
You can deal with arbitrary patterns using a regular expression:
names = {'2name', '3name', '1name', '10name'}
match = regexpi(names,'(?<number>\d+)\D+','names'); % created with regex editor on rubular.com
match = cell2mat(match); % cell array to struct array
clear numbersStr
[numbersStr{1:length(match)}] = match.number; % cell array with number strings
numbers = str2double(numbersStr); % vector of numbers
[B,I] = sort(numbers); % sorted vector of numbers (B) and the indices (I)
clear namesSorted
[namesSorted{1:length(names)}] = names{I} % cell array with sorted name strings
I have a program that takes the columns of a fints-object, multiplies them together pairwise in all combinations and output the result in a new fints object. I have the code for the data, but I also want the series labels to carry through so that the product of column a and b has label a*b.
function tsB = MulTS(tsA)
anames = fieldnames(tsA,1)';
A = fts2mat(tsA);
[i,j] = meshgrid(1:size(A,2),1:size(A,2));
B = Mul(A(:,i(:)),A(:,j(:)));
q = [anames(:,i(:)); anames(:,j(:))];
bnames = strcat(q(1,:),'*', q(2,:));
tsB=fints(tsA.dates, B, bnames);
end
I get warnings when I run it.
tsA= fints([1 2 3]', [[1 1 1]' [2 2 2]'],{'a','b'}');
MulTS(tsA)
??? Error using ==> fints.fints at 188
Illegal name(s) detected. Please check the name(s).
Error in ==> MulTS at 10
tsB=fints(tsA.dates, B, bnames);"
It seems Matlab doesn't like the format of bnames. I've tried googling stuff like "convert cell array to string matlab" and trying things like b = {bnames}. What am I doing wrong?
Your datanames (bnames in MulTS) seems to contain a "*" character, which is illegal according to fints documentation:
datanames
Cell array of data series names. Overrides the default data series names. Default data series names are series1, series2, and so on.
Note: Not all strings are accepted as datanames parameters. Supported data series names cannot start with a number and must contain only these characters:
Lowercase Latin alphabet, a to z
Uppercase Latin alphabet, A to Z
Underscore, _
Try replacing the "*" with "_" or something else.
What is the quickest way to create an empty cell array of strings ?
cell(n,m)
creates an empty cell array of double.
How about a similar command but creating empty strings ?
Depends on what you want to achieve really. I guess the simplest method would be:
repmat({''},n,m);
Assignment to all cell elements using the colon operator will do the job:
m = 3; n = 5;
C = cell(m,n);
C(:) = {''}
The cell array created by cell(n,m) contains empty matrices, not doubles.
If you really need to pre populate your cell array with empty strings
test = cell(n,m);
test(:) = {''};
test(1,:) = {'1st row'};
test(:,1) = {'1st col'};
This is a super old post but I'd like to add an approach that might be working. I am not sure if it's working in an earlier version of MATLAB. I tried in 2018+ versions and it works.
Instead of using remat, it seems even more convenient and intuitive to start a cell string array like this:
C(1:10) = {''} % Array of empty char
And the same approach can be used to generate cell array with other data types
C(1:10) = {""} % Array of empty string
C(1:10) = {[]} % Array of empty double, same as cell(1,10)
But be careful with scalers
C(1:10) = {1} % an 1x10 cell with all values = {[1]}
C(1:10) = 1 % !!!Error
C(1:10) = '1' % !!!Error
C(1:10) = [] % an 1x0 empty cell array