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From |
Christopher F Baum <baum@bc.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Re: data manipulation |

Date |
Fri, 20 Aug 2004 08:12:46 -0400 |

On Aug 20, 2004, at 2:33 AM, Mark wrote:

Hi,Note that if we take the last item to be B C then your problem is that of generating the elements in the lower triangle (strictly, subdiagonal, since you don't want A A) of a symmetric matrix. That sort of thing is easily done with nested loops, where the inner loop's lower index is driven by the upper loop's current index:

I'm struggling with a data manipulation problem: I have a dataset with list

of observations on a string variable and want to create pairwise

combinations. My dataset looks like this:

country1

A

B

C

I need the possible combinations so that the new dataset looks like

country1 country2

A B

A C

C B

set obs 325

g var1 = ""

g var2 = ""

local k 0

local list1 `c(alpha)'

local wc : word count `list1'

forvalues i=1/`wc' {

local f : word `i' of `list1'

forvalues j=`++i'/`wc' {

local s : word `j' of `list1'

local list2 "`list2' `f'`s'"

local ++k

qui {

replace var1 = "`f'" in `k'/`k'

replace var2 = "`s'" in `k'/`k'

}

}

}

di "`list2'"

l var1 var2

Kit

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