Re: st: changing display format of macro contents

[Nick Winter <nw53@cornell.edu>]

This will replace beta1hat with a reformatted version:

   local beta1hat : di %3.2f `beta1hat'

In general, see -whelp extended_fcn-.

Or, using the `expansion_optr' ability (see -whelp macro-) you can do it in 
one step:

  local beta1hat : di %3.2f `=coefs[1,1]'

Or, better yet, omit the beta1hat macro altogether:

  lfit y x , ///
    title("Fitted line: y = `: di %3.2f `=coef[1,2]'' + `: di 3.2f 
`=coef[1,1]'' * x")


--Nick Winter

At 11:08 AM 1/18/2005 -0800, you wrote:

> i want to fit and draw a regression line and label the line, like this:
>
> reg y x
> matrix coefs=e(b)
> loc beta1hat=coefs[1,1]
> loc beta0hat=coefs[1,2]
>
> lfit y x, title("fitted line: y = `beta0hat' + `beta1hat' * x")
>
> when i do this, i get values for the estimated coefficients displayed
> with far more precision than i want.  so i want to display only, say, 2
> digits after the decimal for each macro.  i wasn't able to figure out a
> way to apply a display format to a macro, so i tried adding this code
> before the -lfit- command:
>
> loc beta1hat = int(`beta1hat'*100+0.5)/100
> loc beta0hat = int(`beta0hat'*100+0.5)/100
>
> this works most of the time, but sometimes i get a graph that has a
> title like this:
>
> "y = 7.84000000001 + 2.31 * x"
>
> or
>
> "y = 7.83999999999 + 2.31 * x"
>
> i assume that the problem is the rounding doesn't work in binary all the
> time.  can anyone suggest a way around this?  (obviously if i were
> making a single graph, i could put the coefficients in the title by
> hand, but this code is part of a larger program, so i'd like it
> automated.)
>
> thanks,
> sean.
> _____________________________
>
> please note new contact information:
> _____________________________
>
> sean f. reardon
> associate professor of education and (by courtesy) sociology
> school of education
> 485 lasuen mall, #315
> stanford university
> stanford, ca 94305-3096
> 650.736.8517 (office phone)
> 650.725.7412 (office fax)
> sean.reardon@stanford.edu
> _____________________________
>
>
>
>
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--------------------------------------------------------
Nicholas Winter                           607.255.8819 t
Assistant Professor                       607.255.4530 f
Department of Government              nw53@cornell.edu e
308 White Hall            falcon.arts.cornell.edu/nw53 w
Cornell University
Ithaca, NY 14853-4601 

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