updating/inserting summary array
显示 更早的评论
hi, i have a summary array where it keeps a count of repeated items. e.g
sumarray = {'red', 2; ...
'blue', 3}
etc. While running a for loop, if a red item appears, I simply want to increment the count to 3 for 'red', if a new category comes in e.g. 'pink' I simply want to add a new row {'pink',1}. What is the most efficient way to implement this?
Thanks.
1 个评论
采纳的回答
Image Analyst
2014-5-7
You can use ismember() to check if it's in the list. If it is, increment the second column, if it's not, append it on to the end with a count of 1. See demo code below:
sumarray = {'red', 2; ...
'blue', 3}
% Pick one or the other (red or pink) to test the code.
testWord = 'red'
testWord = 'pink'
column1 = sumarray{:,1}
rowIndex = ismember(testWord, column1, 'rows')
if rowIndex >= 1
sumarray{rowIndex,2} = sumarray{rowIndex, 2} + 1;
else
% Not in there yet. Add it to the end
sumarray{end+1,1} = testWord;
sumarray{end,2} = 1;
end
% See what we ended up with
sumarray
更多回答（1 个）
You would have to test, but here is what I guess is an efficient solution:
colors = {'red', 'black', 'red', 'green', 'red', 'green', 'red'} ;
[uc,~,ic] = unique( colors ) ;
counts = accumarray( ic, 1 ) ;
sumarray = [uc.', num2cell(counts)] ;
For the given dummy set of colors, this outputs
>> sumarray
sumarray =
'black' [1]
'green' [2]
'red' [4]
类别
在 帮助中心 和 File Exchange 中查找有关 Logical 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
