Create a variable which is the difference with n-1 and is named dvariable

Question

I would like to do something like this:

ds, has(type numeric)
    foreach var in `r(varlist)' {
    gen `var' = `var' - `var'[_n-1]
}

I would like to name the new variable simply d+oldname.

How can I combine these two wishes?

Answer 1

I think what you are looking for is something along the following lines perhaps:

sysuse auto, clear

ds, has(type numeric)

foreach var in `r(varlist)' {
    quietly generate d`var' = `var' - `var'[_n-1]           
    display ""
    display "`var'"
    display "d`var'"
}

Which will produce:

price
dprice

mpg
dmpg

rep78
drep78

headroom
dheadroom

trunk
dtrunk

weight
dweight

length
dlength

turn
dturn

displacement
ddisplacement

gear_ratio
dgear_ratio

foreign
dforeign