= SPSS Metadata =

Data about data. SPSS stores metadata within it's 'fat' proprietary format (i.e. SAV). This includes formats, display alignment and width, variable and value labels, measure types (i.e. scale), and user missing values.

For details on variable formats, see [[SPSS/DataTypes#Numeric_Formats|Numeric Formats]] and [[SPSS/DataTypes#String_Formats|String Formats]].

<<TableOfContents>>

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== Examine Metadata ==

To extract metadata from an SPSS data set, use: `display dictionary`. This command works on the active data set.

It outputs (within SPSS) three tables:
 * data file metadata
 * variable metadata
 * value label metadata

The parallel for external data files is:

{{{
sysfile info file="/path/to/file.sav".
}}}

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== Variable Labels ==

To apply labels to variables, try:

{{{
variable label foo "foo"
  bar "bar"
  baz "baz".
}}}

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== Value Labels ==

To apply labels to values, try:

{{{
add value labels foo 1 "1"
 2 "2"
 3 "3"
 /bar 1 "1"
 2 "2"
 3 "3"
 /baz "A" "A"
 "B" "B"
 "C" "C".
}}}

As demonstrated above, labels can be applied to string values.

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== Copy Metadata between Datasets ==

To copy metadata from an existing, formatted data set to another, use `apply dictionary`. This command works on the active data set.

{{{
***** DICT dataset *****.
new file.
input program.

* FOO and BAR will be common variables.
numeric FOO (F2).
string BAR (A2).
* HAM, SPAM, EGGS will either be mismatched or non-existent.
numeric HAM (F8.2).
string SPAM (A8).
numeric EGGS (F8).

end file.
end input program.
execute.

dataset name DICT.
dataset activate DICT.
variable labels
 FOO "FOO"
 BAR "BAR"
 HAM "HAM"
 SPAM "SPAM"
 EGGS "EGGS".
value labels
 /FOO EGGS
  1 "1"
  2 "2".
execute.


***** NEW dataset *****.
new file.
input program.

* FOO and BAR will be common variables.
numeric FOO (F2).
string BAR (A2).
* HAM, SPAM, EGGS will either be mismatched or non-existent.
numeric HAM (F5).
string SPAM (A2).
*numeric EGGS (F8).

end file.
end input program.
execute.
dataset name NEW.
dataset activate NEW.
apply dictionary from "DICT".
}}}

As expected, FOO and BAR have all metadata copied perfectly. The others have some unexpected behaviors.

 * `HAM` is a numeric variable with mismatched formats (`F8.2` in the source, `F5.0` in the target). The target has been overwritten with the source format.
 * `SPAM` is a string variable with mismatched formats (`A8` in the source, `A2` in the target). The source format remains.
 * `EGGS` is defined in the source, but not the target. Its metadata is ''not'' copied over. When it is created after the `apply dictionary`, it is bare of metadata.
   * If the `newvars` subcommand is specified, `EGGS` will be copied over.



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