Reshape Cell to Matrix

Question

Brian 2011-12-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/24527-reshape-cell-to-matrix

I'm receiving a very large quantity of data in a table like format with only 3 columns (Ticker, Return, Date). What I end up with are thousands of instances of the same date and ticker which becomes very inefficient for Matlab to utilize in calculations. I'd like a matrix with Tickers across the columns and dates down the rows. The trick is that not all tickers have a Return for every date so I can't just reshape the matrix based on a unique count of tickers and dates. Does anyone have any idea how to go about doing this? Here's an example of what I'm looking for.

Initial Format

IBM,1.01,1
IBM,1.04,2
IBM,1.06,3
GOOG,.99,1
GOOG,.98,2
AAPL,1,1
AAPL,1.1,2
AAPL,.99,3

Matrix Format below. Where Dates and Tickers would likely be separate arrays. This example should copy to Excel and make it more clear

,AAPL,GOOG,IBM
1,1,99,1.01
2,1.1,.98,1.04
3,.99,Nan,1.06

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Answer 1

Andrei Bobrov 2011-12-22

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/24527-reshape-cell-to-matrix#answer_32234

在 MATLAB Online 中打开

EDIT [13:20MSK 23.12.2011]

data = {'IBM',1.01,1
'IBM',1.04,2
'IBM',1.06,3
'GOOG',.99,1
'GOOG',.98,2
'AAPL',1,1
'AAPL',1.1,2
'AAPL',.99,3};
[a,b,b] = unique(data(:,1));
d23 = cell2mat(data(:,2:3));
N = max(d23(:,2));
outdata = accumarray([d23(:,2),b],d23(:,1),[N numel(a)],[],NaN)
out = [{'Name'} a';num2cell([(1:N)',outdata])]

OR

out = [{'Name'},a';...
 num2cell((1:N)'),accumarray([d23(:,2),b],d23(:,1),[N numel(a)],@(x){x},{NaN})];

small corrected in [N numel(a)]

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Brian 2011-12-23

Pure Genius. Extremely useful function that accumarray, I couldn't figure out how to use it properly but I believe I understand it now looking at your revisions. Thanks so much for taking the time to help.

Brian

Brian 2011-12-27

So I'm having an issue adjusting this function to work with my actual dataset and it may be because I still don't understand the function quite right.

My actual dataset format is as follows....

data = {'06/03/2011','00163T10'

'06/06/2011','00163T10'

'06/07/2011','00163T10'

'06/03/2011','ABCDEFGH'

'06/06/2011','ABCDEFGH'

'06/07/2011','ABCDEFGH'

'06/03/2011','ABCDWXYZ'

'06/06/2011','ABCDWXYZ'};

How would I go about using the arguments above with a dataset in this format. Ultimately, I am attempting to create a logical matrix of whether the ticker was in or out (1 or 0) for each given day.

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