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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
RE: st: saving space while recoding |

Date |
Mon, 26 Jul 2010 14:14:42 +0200 |

<> For -irecode- also try http://www.stata-journal.com/article.html?article=st0181 HTH Martin -original message- Subject: Re: st: saving space while recoding From: Jeph Herrin <stata@spandrel.net> Date: 26-07-2010 14:07 You find -irecode- useful: gen var = irecode(newvar2,22,25,.)-1 hth, Jeph On 7/25/2010 10:14 PM, sarah plank wrote: > Now I have a second list given me where there are some ranges instead > of single cutoff points, so for list "newvar2 22 25 newvar3 33.5 > 26 newvar9 55.5 100 " I need to recode values less than first > range point to -1, values between range to zero, and points above the > second range point to 1. With the replace command, I can do it: > generate var = -1 if newvar2<=22 > replace var = 0 if newvar2>=22& newvar2<=25 > replace var = 1 if newvar2>= 25& newvar2!=. > > and I tried to paste this into the code I got earlier but it doesnt work. > gen var = cond(22<=newvar2<=25, 0, cond(missing(newvar2), ., > (cond(newvar2<22, -1, 1)) > > This gives me all zeros ! How can I edit this code to work with my > new list and make this work in a loop to save space ? > > > > > > On Sat, Jul 24, 2010 at 5:58 PM, sarah plank<sarahkplank@gmail.com> wrote: >> Oh my gosh, how great! I copied and pasted my list into the first >> example and it is working, I am running it now but I hope it doesnot >> break because I dont understand it enough to make changes. Thanks. >> >> On Sat, Jul 24, 2010 at 4:35 PM, Eric Booth<ebooth@ppri.tamu.edu> wrote: >>> <> >>> >>> >>> There are a couple of possibilities here. First, you can get rid of the 3 -replace- statements with one -recode- statement that does the same thing, e.g., >>> >>> ******! >>> recode polyclornew (min/44 = -1) (45=0) (46/max = 1) (.=.) >>> ******! >>> >>> but this doesn't make managing your long list of recode conditions much easier. Also, a warning: note that the -replace- codes in your example will not recode any values between 44 and 45 (such as 44.5) nor values between 45& 46. Given that a lot of the values in the list your provided aren't integers, this might be a concern. >>> >>> In terms of making your code shorter you might consider using the -cond()- function. For example, >>> **********************! >>> sysuse auto, clear >>> keep price >>> qui g i = cond(price==4099, 0, cond(missing(price), ., (cond(price<4099, -1, 1)))) >>> sort price >>> **********************! >>> will recode price around the 4,099 threshold. >>> A brief explanation of what this code is doing is probably helpful here: if price is == 4099 it will recode i to 0. If not, it will evaluate the last "cond(missing(price), ., (cond(price<4099, -1, 1)) " part. Within this last part it will recode i to -1 if price is less than 4099 and i to 1 if price is greater than or equal to 4099 (but it has already recoded to 0 if price is equal to 4099, so it will just recode to 1 if price is greater than 4099 in this case) . See -help cond- for more. >>> >>> To make this work with a long list of conditions like the ones you have provided, you could break the list up into macros&/or use -tokenize- to loop over the pairs of items in your list. Here are two examples using the -auto.dta- again: >>> >>> >>> **********************! >>> //EXAMPLE 1// >>> /* >>> This example uses the list if it is formatted as you presented it in your posting--it will make the changes to items 1 (mpg) and 2(23) in the list and then move on the items 3 and 4 in the list and so on to the end >>> */ >>> >>> sysuse auto, clear >>> local list mpg 23 rep78 3 turn 17 weight 2930 length 196 >>> ** >>> token `"`list'"' >>> di `"`list'"' >>> while "`1'" != "" { >>> di "recode `1' for value `2'" >>> g i`1' = cond(`1'==`2', 0, cond(missing(`1'), ., (cond(`1'<`2', -1, 1)))) >>> mac shift 2 //this part increases the macro `1' by 2 to `3' >>> } >>> sort mpg >>> order *mpg >>> **********************! >>> >>> Alternatively, if your list were organized down a column in a spreadsheet or something, you could add -local- and a macname to each pair of items to be used for the recodes and loop over each condition. >>> >>> **********************! >>> //EXAMPLE 2// >>> sysuse auto, clear >>> >>> **items in your list: >>> local one mpg 23 >>> local two rep78 3 >>> local three turn 17 >>> local four weight 2930 >>> local five length 196 >>> >>> foreach x in one two three four five { >>> token ``x'' >>> di "``x''" >>> di "recode `1' for value `2'" >>> g i`1' = cond(`1'==`2', 0, cond(missing(`1'), ., (cond(`1'<`2', -1, 1)))) >>> } >>> sort mpg >>> order *mpg >>> **********************! >>> >>> ~ Eric >>> __ >>> Eric A. Booth >>> Public Policy Research Institute >>> Texas A&M University >>> ebooth@ppri.tamu.edu >>> Office: +979.845.6754 >>> >>> >>> >>> >>> >>> On Jul 24, 2010, at 4:22 PM, sarah plank wrote: >>> >>>> I need to create a recode but save some space in my code. I have >>>> lots of recodes where I am given the variable to recode and the cutoff >>>> point over which to recode the variables. So, given my list of >>>> "polyclor 23.4 polyclor2 33.3 pavol 45 genpt 1.11 gnpt 1 on >>>> 0 offon 0 offon2 1 got5 66 {+ 670 more items}" I need to recode >>>> them all by their cutoff in the list, so >>>> >>>> clonevar polyclor2 = polyclornew >>>> replace polyclornew = -1 if polychlornew<44 >>>> replace polyclornew = 0 if polyclornew==45 >>>> replace polyclornew = 1 if polyclornew>46& polyclornew!=. >>>> tab polyclornew >>>> >>>> but this is so exhausting for so many values and so long in the >>>> do-code. How can I make this in less space ? >>>> >>>> * >>>> * 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/ > * * 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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