array: concatenate two columns of integers to one colum
3 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
(Matlab novice)
I thought this would be so easy...
I have a 2-d array of integers and I want to combine two columns like this:
... 123 456 ...
... 123 456 ...
etc...
I want:
... 123456 ...
... 123456 ...
etc...
as single numbers (that is, I want (123 * 1000) + (456)
The number of rows will be variable from one run to the next.
Any help would be appreciated.
1 Kommentar
Jan
am 13 Sep. 2012
The question is not clear. What is the wanted output for: [1,2,3,4; 5,6,7,8; 9,10,11,12] ?
Akzeptierte Antwort
Honglei Chen
am 13 Sep. 2012
Bearbeitet: Honglei Chen
am 13 Sep. 2012
a = randi([1 100],[5 4]) % a 5x4 integer matrix
b = cellfun(@num2str,{a(:,2:3)},'UniformOutput',false)
c = cellfun(@(x) strrep(x,' ',''), cellstr(b{1}),'UniformOutput',false)
a(:,2) = str2double(c)
a(:,3) = []
2 Kommentare
Honglei Chen
am 13 Sep. 2012
@Jan, thanks for the tip. That's a good one. I think you missed a b in your second expression.
Weitere Antworten (4)
Jan
am 13 Sep. 2012
Bearbeitet: Jan
am 13 Sep. 2012
A = [1234, 567; 1, 234];
B = A(:, 1) .* nextpow10(A(:, 2)) + A(:, 2);
function Y = nextpow10(X)
Y = 10 .^ floor(log10(abs(n)) + 1); % [EDITED]
Please test this before using, I cannot run Matlab currently.
1 Kommentar
Andrei Bobrov
am 13 Sep. 2012
Bearbeitet: Andrei Bobrov
am 13 Sep. 2012
A=randi(67,6,4)
n = ceil(log10(A(:,2:end)));
out = sum(A(:,1:end-1).*(10.^fliplr(cumsum(fliplr(n),2))),2)+ A(:,end)
William Sampson
am 13 Sep. 2012
2 Kommentare
Honglei Chen
am 13 Sep. 2012
It's the same. I updated my answer to show an example of combining 2nd and 3rd column of a matrix
Jan
am 13 Sep. 2012
Bearbeitet: Jan
am 13 Sep. 2012
See my suggestion:
B = rawData(:, 9) .* nextpow10(rawData(:, 10)) + rawData(:, 10)
result = [rawData(:, 1:8), B, rawData(:, 11:end)]
I do not see, why the suggested method should not work.
Btw. What do you expect as result of two 16 digit numbers? You can store only 16 digits in variables of the type DOUBLE.
Ryan
am 13 Sep. 2012
Bearbeitet: Ryan
am 13 Sep. 2012
A = [1234, 567; 1, 234]; %Sample Data
% Figure out how many spaces to shift the left column
C = ceil(log10(A(:,2)));
% Find areas where the value is a multiple of 10 or is 1
idx = A(:,2) == 1 | rem(A(:,2),10) == 0;
C(idx) = C(idx) + 1; % Handle the exception
% Determine how much to shift the left column
C = 10.^C;
% Add in the right column
A = A(:,1).*C + A(:,2);
0 Kommentare
Siehe auch
Kategorien
Mehr zu Matrices and Arrays finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!