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help for labvalch
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Copy and/or delete value labels

  labvalch valuelabelname , [ { from(numlist) to(numlist) | swap(#1 #2) }
           delete(numlist) list ]


Description

labvalch copies and/or deletes specified value labels from value label
valuelabelname.

Any label define whatever , modify command that executes changes is echoed to
the monitor.


Remarks 

Suppose that variable gender is coded 1 for male and 2 for female by

    . label def gender 1 "male" 2 "female"
 
    . label val gender gender

but we find it convenient to change to 0 and 1:

    . replace gender = gender - 1

We need also to change the value labels. Slow but sure is

    . label def gender 0 "male" 1 "female", modify

It would normally be best to clean up by also deleting the label for 2:

    . label def gender 0 "male" 1 "female" 2 "", modify

An alternative is

    . labvalch gender, f(1 2) t(0 1)

Again, it would normally be best to clean up by also deleting the label for 2:

    . labvalch gender, f(1 2) t(0 1) delete(2)

Suppose we have a set of labels

    . label def rating 1 "poor" 2 "fair" 3 "OK" 4 "good" 5 "excellent"

and we wish to reverse the labelling. This is done by

    . labvalch rating, f(1/5) t(5/1)


Options

from(numlist) specifies a numlist of integers whose value labels are to be
    copied. These labels will not be changed unless an element of the numlist
    also appears in to( ), or unless they are deleted by delete().  Specifying
    an integer for which a label does not exist is treated as an error.

to(numlist) specifies a numlist of integers whose value labels are to be
    defined. Existing value labels are modified.

All replacements take place independently. Thus from(2 1) to(1 2) would swap
value labels associated with 1 and 2: the label of 2 becomes that of 1, and
vice versa. (swap(1 2) would be another way to do this.)

from() and to() must contain the same number of elements after expansion. This
syntax may not be combined with swap().

swap(#1 #2) specifies two integers possessing value labels whose labels are to
    be swapped. This syntax may not be combined with from() to().

delete(numlist) specifies a numlist of integers whose value labels are to be
    deleted. Note that all deletions take place after copying.  Specifying an
    integer for which a label does not exist is not treated as an error, but
    this will be noted.

list invokes label list valuelabelname after the changes produced.

    
Examples 

    . labvalch rating, f(1/5) t(5/1)

    . labvalch foo, f(1 1 1 1) t(2/5)

    . foreach label in a b c d e {
    .        labvalch `label', f(1 2) t(0 1) delete(2)
    . }


Author 

         Nicholas J. Cox, University of Durham, U.K.
         n.j.cox@durham.ac.uk


Acknowledgements 

        Fred Wolfe made interesting and helpful comments on 
        labcopy and labdel, precursors of this command.


Also see

 Manual:   [U] 15.6, [R] label, [R] recode 
On-line:  help for label; numlist; recode; labedit (if installed)