Dear Statalisters,
In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) scalar b2 = exp(_b[x]) // beta and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example quietly replace b2=scalar(b1) in `i' That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). scalar hig = 1 if (w1 > w2) & (w1 > w3) scalar hig = 2 if (w2 > w1) & (w2 > w3) scalar hig = 3 if (w3 > w1) & (w3 > w1) However, -if- is not allowed in combination with -scalar-. Anyone know a better solution for this. /Tomas * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
A command
... if <condition> applies observation by observation and can not be what you want. I guess that you want if (w1 > w2) & (w1 > w3) { scalar hig = 1 } else if (w2 > w1) & (w2 > w3) { scalar hig = 2 } else if (w3 > w1) & (w3 > w2) { scalar hig = 3 } These sound like "w1 biggest", "w2 biggest", "w3 biggest". If there are any ties w1 == w2 | w2 == w3 your scalar will be undefined. (I've corrected what looks like a typo in your code, but not this problem with ties, which is perhaps unlikely.) Nick [hidden email] Tomas Lind In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) scalar b2 = exp(_b[x]) // beta and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example quietly replace b2=scalar(b1) in `i' That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). scalar hig = 1 if (w1 > w2) & (w1 > w3) scalar hig = 2 if (w2 > w1) & (w2 > w3) scalar hig = 3 if (w3 > w1) & (w3 > w1) However, -if- is not allowed in combination with -scalar-. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Tomas Lind-2
Something like this?
forv i = 1/3 { scalar w`i' = ceil(10*runiform()) } if scalar(w1) > scalar(w2) & scalar(w1) > scalar(w3) { scalar hig = 1 } else if scalar(w2) > scalar(w1) & scalar(w2) > scalar(w3) { scalar hig = 2 } else if scalar(w3) > scalar(w1) & scalar(w3) > scalar(w2) { scalar hig = 3 } else { scalar hig = 0 } scalar list _all Scott On Wed, Nov 17, 2010 at 9:27 AM, Tomas Lind <[hidden email]> wrote: > Dear Statalisters, > > In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) > > scalar b2 = exp(_b[x]) // beta > > and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example > > quietly replace b2=scalar(b1) in `i' > > > That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). > > scalar hig = 1 if (w1 > w2) & (w1 > w3) > scalar hig = 2 if (w2 > w1) & (w2 > w3) > scalar hig = 3 if (w3 > w1) & (w3 > w1) > > However, -if- is not allowed in combination with -scalar-. > > Anyone know a better solution for this. > > /Tomas > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Tomas Lind-2
--- On Wed, 17/11/10, Tomas Lind wrote:
> Now I want to calculate "hig" (in the > bottom of the loop) and save it in the dataset with > aggregated data (where w1, w2, w3 are -scalars-). > > scalar hig = 1 if (w1 > w2) & (w1 > w3) > scalar hig = 2 if (w2 > w1) & (w2 > w3) > scalar hig = 3 if (w3 > w1) & (w3 > w1) > > However, -if- is not allowed in combination with > -scalar-. -if- after a command is supposed to work on the dataset, i.e. the result is a vector of trues and falses, one for each observation in the dataset. This is why -scalar- cannot handle it: it needs to be fed one number. -if- on its own or before a command is supposed to work on its own and will result in a scalar outcome either true or false. So you could get your scalar -hig- by: if (w1 > w2) & (w1 > w3) scalar hig = 1 if (w2 > w1) & (w2 > w3) scalar hig = 2 if (w3 > w1) & (w3 > w1) scalar hig = 3 or: if (w1 > w2) & (w1 > w3) { scalar hig = 1 } if (w2 > w1) & (w2 > w3) { scalar hig = 2 } if (w3 > w1) & (w3 > w1) { scalar hig = 3 } or: scalar hig = cond( (w1 > w2) & (w1 > w3), 1, /// cond( (w2 > w1) & (w2 > w3), 2, /// cond( (w3 > w1) & (w3 > w1), 3, .))) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Nick Cox
As Scott Merryman's similar solution underlines,
the code here optimistically assumes no clash between scalar and variable names. Wrapping with -scalar()- means being always safe and never sorry. Nick [hidden email] -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Nick Cox Sent: 17 November 2010 16:12 To: '[hidden email]' Subject: st: RE: scalar do not allow -if- A command ... if <condition> applies observation by observation and can not be what you want. I guess that you want if (w1 > w2) & (w1 > w3) { scalar hig = 1 } else if (w2 > w1) & (w2 > w3) { scalar hig = 2 } else if (w3 > w1) & (w3 > w2) { scalar hig = 3 } These sound like "w1 biggest", "w2 biggest", "w3 biggest". If there are any ties w1 == w2 | w2 == w3 your scalar will be undefined. (I've corrected what looks like a typo in your code, but not this problem with ties, which is perhaps unlikely.) Nick [hidden email] Tomas Lind In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) scalar b2 = exp(_b[x]) // beta and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example quietly replace b2=scalar(b1) in `i' That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). scalar hig = 1 if (w1 > w2) & (w1 > w3) scalar hig = 2 if (w2 > w1) & (w2 > w3) scalar hig = 3 if (w3 > w1) & (w3 > w1) However, -if- is not allowed in combination with -scalar-. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Maarten buis
Thanks Nick, Scott and Maarten,
Many thanks for helpful code and helpful comments and explanations. /Tomas -----Ursprungligt meddelande----- Från: [hidden email] [mailto:[hidden email]] För Maarten buis Skickat: den 17 november 2010 17:17 Till: [hidden email] Ämne: Re: st: scalar do not allow -if- --- On Wed, 17/11/10, Tomas Lind wrote: > Now I want to calculate "hig" (in the > bottom of the loop) and save it in the dataset with aggregated data > (where w1, w2, w3 are -scalars-). > > scalar hig = 1 if (w1 > w2) & (w1 > w3) scalar hig = 2 if (w2 > w1) > & (w2 > w3) scalar hig = 3 if (w3 > w1) & (w3 > w1) > > However, -if- is not allowed in combination with -scalar-. -if- after a command is supposed to work on the dataset, i.e. the result is a vector of trues and falses, one for each observation in the dataset. This is why -scalar- cannot handle it: it needs to be fed one number. -if- on its own or before a command is supposed to work on its own and will result in a scalar outcome either true or false. So you could get your scalar -hig- by: if (w1 > w2) & (w1 > w3) scalar hig = 1 if (w2 > w1) & (w2 > w3) scalar hig = 2 if (w3 > w1) & (w3 > w1) scalar hig = 3 or: if (w1 > w2) & (w1 > w3) { scalar hig = 1 } if (w2 > w1) & (w2 > w3) { scalar hig = 2 } if (w3 > w1) & (w3 > w1) { scalar hig = 3 } or: scalar hig = cond( (w1 > w2) & (w1 > w3), 1, /// cond( (w2 > w1) & (w2 > w3), 2, /// cond( (w3 > w1) & (w3 > w1), 3, .))) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Nick Cox
--- Nick wrote:
> the code here optimistically assumes no clash between scalar > and variable names. > > Wrapping with -scalar()- means being always safe and never > sorry. An alternative solution that I often prefer (mostly because I am used to it) is: tempname w1 w2 w3 scalar `w1' = ... scalar `w2' = ... scalar `w3' = ... Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
I agree in terms of my own programming.
The original question was focused on saving scalars as results, in which case temporary names that disappear when a program has finished are of no use. There is a middle way. Within a -program- (declared as such) use temporary names for scalars as here, and then when all is done use -return- or -ereturn- to define scalars as r() or e() class results. A broader discussion is accessible at SJ-6-2 dm0021 . Stata tip 31: Scalar or variable? Problem of ambiguous names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. I. Kolev Q2/06 SJ 6(2):279--280 (no commands) tips for avoiding abbreviation conflicts with variables when naming scalars Nick [hidden email] Maarten buis --- Nick wrote: > the code here optimistically assumes no clash between scalar > and variable names. > > Wrapping with -scalar()- means being always safe and never > sorry. An alternative solution that I often prefer (mostly because I am used to it) is: tempname w1 w2 w3 scalar `w1' = ... scalar `w2' = ... scalar `w3' = ... * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
In reply to this post by Nick Cox
On Wed, Nov 17, 2010 at 11:11 AM, Nick Cox <[hidden email]> wrote:
> A command > > ... if <condition> > > applies observation by observation and can not be what you want. > > I guess that you want > > if (w1 > w2) & (w1 > w3) { > scalar hig = 1 > } > else if (w2 > w1) & (w2 > w3) { > scalar hig = 2 > } > else if (w3 > w1) & (w3 > w2) { > scalar hig = 3 > } > > These sound like "w1 biggest", "w2 biggest", "w3 biggest". If there are any ties w1 == w2 | w2 == w3 your scalar will be undefined. (I've corrected what looks like a typo in your code, but not this problem with ties, which is perhaps unlikely.) > > Nick > [hidden email] > > Tomas Lind > > In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) > > scalar b2 = exp(_b[x]) // beta > > and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example > > quietly replace b2=scalar(b1) in `i' > > > That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). > > scalar hig = 1 if (w1 > w2) & (w1 > w3) > scalar hig = 2 if (w2 > w1) & (w2 > w3) > scalar hig = 3 if (w3 > w1) & (w3 > w1) > > However, -if- is not allowed in combination with -scalar-. the scalar version of -if- is cond(): scalar hig = cond(w2>w1,cond(w3>w2,3,2),cond(w3>w1,3,1)) although if in your example you had w1,w2,...w100, you wouldn't want to write anything like the above. you would then program one -forvalues- loop and one -if- branch that updates the index of the max element. Best, Sergiy Radyakin > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
Yes and no; the code is good, but the commentary could be misleading.
You can certainly use -cond()- to define these scalars, as others have already pointed out in this thread. But its role is not analogous to that of the -if- qualifier. -if- qualifiers apply conditionally to a subset of observations (which may be empty or the whole set), but no such notion applies to scalars. Nick [hidden email] Sergiy Radyakin the scalar version of -if- is cond(): scalar hig = cond(w2>w1,cond(w3>w2,3,2),cond(w3>w1,3,1)) although if in your example you had w1,w2,...w100, you wouldn't want to write anything like the above. you would then program one -forvalues- loop and one -if- branch that updates the index of the max element. On Wed, Nov 17, 2010 at 11:11 AM, Nick Cox <[hidden email]> wrote: > A command > > ... if <condition> > > applies observation by observation and can not be what you want. > > I guess that you want > > if (w1 > w2) & (w1 > w3) { > scalar hig = 1 > } > else if (w2 > w1) & (w2 > w3) { > scalar hig = 2 > } > else if (w3 > w1) & (w3 > w2) { > scalar hig = 3 > } > > These sound like "w1 biggest", "w2 biggest", "w3 biggest". If there are any ties w1 == w2 | w2 == w3 your scalar will be undefined. (I've corrected what looks like a typo in your code, but not this problem with ties, which is perhaps unlikely.) Tomas Lind > In a small simulation I generate data and analyze them with 3 regression methods. In the bottom of the loop I save (among other things) > > scalar b2 = exp(_b[x]) // beta > > and then put the -scalar- values into a variable in a dataset where I collect the results from the 1000 simulated datasets. For example > > quietly replace b2=scalar(b1) in `i' > > > That works fine. Now I want to calculate "hig" (in the bottom of the loop) and save it in the dataset with aggregated data (where w1, w2, w3 are -scalars-). > > scalar hig = 1 if (w1 > w2) & (w1 > w3) > scalar hig = 2 if (w2 > w1) & (w2 > w3) > scalar hig = 3 if (w3 > w1) & (w3 > w1) > > However, -if- is not allowed in combination with -scalar-. > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ |
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