Reshape Cell to Matrix
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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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采纳的回答
Andrei Bobrov
2011-12-22
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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