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Re: st: saving space while recoding
From
Jeph Herrin <[email protected]>
To
[email protected]
Subject
Re: st: saving space while recoding
Date
Mon, 26 Jul 2010 08:07:03 -0400
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<[email protected]> 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<[email protected]> 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
[email protected]
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 ?
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