Drop the last 4 characters of a string

[Francois Durant]

Hi,

I would like to remove the last 4 characters of a string. here is the data:

stockidentifier
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX
AHD.ASX

I have tried to use the command "substr" but I could not figure out the right syntax. Thanks!

[Joseph Coveney]

generate str stock_prefix = substr(stockidentifier, 1, strlen(stockidentifier) - 4)

[Francois Durant]

Would you be able to explain the syntax? I thought that the second number was the position.

I have several stock identifiers that have a stock prefix longer than 3 characters. For instance: ABCDED.ASX. Is that still the right syntax?

[Carlo Lazzaro]

Francois:
you can start with eliminating what lies after the full stop:

set obs 1
g stockidentifier="AHD.ASX"
split stockidentifier , p(.)
drop stockidentifier2

[Nick Cox]

substr()

is a function (not a command!). The distinction is important because commands and functions are quite distinct in Stata (whether that is so for other software is a different question). Thus functions have different syntax and are documented separately.

It seems that you want to eliminate the suffix such as ".ASX".

Joseph's method is fine so long as the suffix has that length.

Assuming that the suffix starts with a stop (period) and there is no such character earlier, then another way to do it (the same as that used inside split) is

gen id2 = substr(id, 1, strpos(id, ".") - 1) 

Remember that help on any function is directly obtainable by a call such as

help substr()

That is, spelling out parentheses flags to Stata that you are interested in the function named.

[Joseph Coveney]

Would you be able to explain the syntax? I thought that the second number was the position.

It is.

You want the remove the last four characters. To do so, you calculate the position of the last character (using the strlen() function) and then subtract four from it.

I have several stock identifiers that have a stock prefix longer than 3 characters. For instance: ABCDED.ASX. Is that still the right syntax?

Yes. It doesn't matter how long the prefix is—if you want to remove the last four characters, then it is the still the right syntax.