SPSS Alter Type
The ALTER TYPE command changes the data type of a variable.
Contents
Uaage
alter type foo bar baz (F1.0). alter type ham (ADATE10) spam eggs (A10).
The AMIN and AHEXMIN keywords can be used to dynamically capture the minimum length a string variable can be set to without truncating data. For example:
alter type all (a = amin).
Furthermore, basic arithmetic can be used with these keywords. AMIN + 2 or AMIN + 25% set string lengths to the minimum required length plus 2 characters, or plus 25% of that length.
To set formats conditionally, i.e. set ADATE10 on variables that are formatted as A10 but ADATE11 on variables that are formatted as A11, try:
alter type foo bar baz (A10 = ADATE10). alter type foo bar baz (A11 = ADATE11).
By default, SPSS will display the list of variables that were altered with the old and new formats. Add the /PRINT=ALTEREDTYPES subcommand to explicitly allow this behavior.
To display the first 25 cases for which the alteration caused potentially lossy conversion (i.e. between string and numeric formats), add the /PRINT=ALTEREDVALUES subcommand.
Not that ALTEREDTYPES and ALTEREDVALUES can be used together.
To display nothing, add the /PRINT=NONE subcommand.
Data Model
ALTER TYPE is executed immediately. If there are pending transformations, they are executed first.
The active dataset is read only if there were pending transformations or if the AMIN/AHEXMIN keywords were used.