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From |
"Cohen, Elan" <[email protected]> |

To |
"[email protected]" <[email protected]> |

Subject |
st: RE: Making a matrix out of three variables |

Date |
Thu, 16 Jan 2014 21:08:05 +0000 |

```
I'm going to assume that C is numeric since 1) Stata matrices cannot be strings (outside of -mata-), and 2) you state that your variable is numeric (despite what you show). I'm also using nested loops, but unless your matrix is really large, this shouldn't run too slowly.
See below for code.
HTH,
- Elan
clear
input str2 A str2 B C
A1 A1 1
A1 A2 2
A1 A4 3
A1 A5 4
A2 A2 5
A2 A1 6
A2 A3 7
end
bys A B: assert _N==1
qui levelsof A, clean
loc rownames `r(levels)'
qui levelsof B, clean
loc colnames `r(levels)'
loc r : word count `rownames'
loc c : word count `colnames'
mat M = J(`r',`c',0)
mat rownames M = `rownames'
mat colnames M = `colnames'
foreach r in `rownames' {
foreach c in `colnames' {
su C if A=="`r'" & B=="`c'", meanonly
if `r(N)'>0 {
mat M[rownumb(M,"`r'"), colnumb(M,"`c'")] = r(mean)
}
}
}
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Eilya Torshizian
Sent: Thursday, January 16, 2014 15:03
To: [email protected]
Subject: st: Making a matrix out of three variables
Dear Statalist members,
I need to convert three variables to a matrix. The values of variable A and B should be used as row and column names of the output matrix. Let's assume three columns of data, where A, B and C are the name of my numeric variables,
A B C
A1 | A1 | C1
A1 | A2 | C2
A1 | A4 | C3
A1 | A5 | C4
A2 | A2 | C5
A2 | A1 | C6
A2 | A3 | C7
I need to convert these to the following matrix,
A1 A2 A3 A4 A5
A1 C1 C2 0 C3 0
A2 C6 C5 C7 0 0
As I have a wide range of observations, I would like to avoid nested loops.
Thanks,
Eilya.
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```

**References**:**st: Making a matrix out of three variables***From:*Eilya Torshizian <[email protected]>

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