generating a numeric variable from the string variable containing letters and numbers

[Mina Wu]

Dear all,

I would like to construct a numeric variables from the string variable that contains letters and numbers combined. The structure of the variable does not allow me to use

destring, replace

option. The string variables ("string") and the variable I want to create ("numeric") are as follows:

String Numeric
RS123456 123456
RS098766 098766

...

Basically, I do not want RS part of the string variable.

I tried using the following command:
[QUOTE]
gen str1 Numeric = substr("String",3,.)
destring Numeric, replace
/QUOTE]

However the first command of the two does not work. I usually get just one digit extracted (the third digit-1 and 0 respectively) instead of all 6.

Any help would be much appreciated!

Thank you!

[Carlo Lazzaro]

Mina:
the following ought to work:

g str_1=substring("RS123456",3,.)
destring str_1=, g(Numeric)

[Mina Wu]

Carlo, thank you for the answer!


that command works for a single observations of the variable "String". However, "String" (illustrated in the first post) consists of thousands of similar observations (i.e "RSxxxxx" where xxx are some numbers). How can I apply this command to all the observations within variable "String"?


Thank you in advance!

[Carlo Lazzaro]

Mina:
as from your first post, I understood that the numeric code in your string started always from the third position.
If this is not the case for all your strings, that code can accomplish only a part of the desired task.

[Mina Wu]

Carlo, you are right. The numeric code in my string variable "String" starts from the third position.

I do not understand why the commands you proposed contains a single observations "RS123456" instead of the variable name ("String")? this is the issue-i can only generate (with the proposed command given below) a variable containing a single numeric value ("123456"), which is not what I want. I want the letters "RS" to disappear from all the observations within "String" variable. Hence, I want to extract numeric code starting from the 3rd position of "String".

Is this possible?

many thanks again!!
g str_1=substring("RS123456",3,.) destring str_1=, g(Numeric)

[Carlo Lazzaro]

Mina:
you may want to take a look at http://www.ats.ucla.edu/stat/stata/faq/regex.htm

[Nick Cox]

Some confusion here. Mina should feed the name of the string variable first. If the variable is named String, then

gen Numeric = substr(String, 3, .)
destring Numeric, replace

should work and indeed you can get straight to where you want to be with

gen Numeric = real(substr(String,3,.))

Note that insisting on str1 will not help here. The consequence should always be a string variable containing at most one character. That's what str1 means.

Clearly you will need to use the actual variable name.

[Mina Wu]

Thank you very much for all the inputs! In the end, the single needed command was:

gen Numeric = real(substr(String,3,.))

to solve my issue! Many thanks!
Mina

[Fabiola]

Dear all,

I have a list of codes (e.g., C03 CFD HHTRDE) and I want to create a variable Y that is equal to 1 if a string variable X has any of these codes, but the codes need to start the variable x.

Here is what I need:

If x=C03T0F; y=1
If x=XTSC03; y=0
if x=XTC03N; y=0

if x=CFD003; y=1
if x=DDCFD; y=0

I would appreciate it if you could help me.

Thanks in advance for your help