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| = SPSS Formats = SPSS supports numeric variables and strings, with conversion options and some automatic conversion functionality. There are several formats on top of numerics that impact visualization, not storage. |
= SPSS Data Types = SPSS exposes numeric and string data types. Certain specialized forms of data are handled by formats that impact visualization and export, not storage. The primary example of this is date and time data. <<TableOfContents>> |
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| == Datetime == | == Numeric Data == |
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| === A warning about data input === | Numeric data is stored as double-precision floating point. |
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| SPSS tries to be clever about reading data. Under the format `TIME`, all of these are read in as `"01:02"`, even though the format is a minimum of 5-wide: * `"1:2"` * `"01 2"` * `"01:02"` Under the format `DATE`, all of these are read in as `"28-OCT-90"`: * `"28-OCT-90"` * `"28/10/1990"` * `"28.OCT.90"` * `"28 October, 1990"` === Datetime formats === ||'''Format''' ||'''Appears as...''' ||'''Note''' || ||DATETIME20 ||`dd-MMM-yyyy hh:mm:ss` ||`MMM` is as JAN, not 001|| ||DATETIME18 ||`dd-MMM-yyyy hh:mm` ||`MMM` is as JAN, not 001|| ||DATE11 ||`dd-MMM-yyyy` ||`MMM` is as JAN, not 001|| ||DATE7 ||`dd-MMM-yy` ||`MMM` is as JAN, not 001|| ||TIME8 ||`hh:mm:ss` || || ||TIME5 ||`hh:mm` || || ||ADATE10 ||`mm/dd/yyyy` || || ||ADATE8 ||`mm/dd/yy` || || ||EDATE10 ||`dd.mm.yyyy` || || ||EDATE8 ||`dd.mm.yy` || || |
Generally, numeric data uses either a numeric format (`Fw.d` where `w` is the field width and `d` is the number of visible decimal places) or a restricted numeric format (`Nw`) for displaying data. See [[SPSS/DataFormats#Print_Formats|here]] for further information. The default format, which will be applied to any implicitly declared variables, is `F8.2`. |
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| === Parse Timestamps === | === Date and Time Data === |
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| A macro for timestamp conversion, from `dd/mm/yyyy hh:mm` to SPSS `DATETIME20`: | Dates are stored as the number of seconds from midnight, October 14, 1582 to midnight on the specified date. Generally the `DATE10` format is used for displaying data. |
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| {{{ define !str2datetime (in=!tokens(1) / out=!cmdend) numeric !out (DATETIME20). compute !out = date.mdy( number(char.substr(!in,1,2), f2), number(char.substr(!in,4,2), f2), number(char.substr(!in,7,4), f4) ) + time.hms( number(char.substr(!in,12,2), f2), number(char.substr(!in,15,2), f2), 0 ) . !enddefine. |
Datetimes are stored as the number of seconds to the specified time on the specified date. Generally the `DATETIME20` format is used for displaying data. |
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| !str2datetime in=mytimestampvar out=mydatetimevar. }}} |
Times are stored as the number of seconds. This ''can'' be imagined as the number of seconds from midnight to the specified time, but that is not a ''necessary'' construct. Generally the `TIME8` format is used for displaying data. Keep in mind that 1 day = 60 (seconds) * 60 (minutes) * 24 (hours) = 86400 seconds. For more information about date and time formats, see [[SPSS/DataFormats#Print_Formats|here]]. See [[SPSS/DatetimeFunctions|here]] for the built-in library of date and time functions. |
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| == Numerics == | == String Data == |
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| Formats only truncate the displayed value, or the value translated into data files. SPSS always retains data to original precision. | String data is stored at a fixed length. |
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| Given 123.45... | A string variable can only be explicitly declared, as by the [[SPSS/String|STRING]] command. |
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| ||'''Format''' ||'''Using...''' ||'''Appears as...''' || ||Fw ||F8 ||123 || ||Fw.d ||F8.1 ||123.4 || ||Nw ||N8 ||00000123 || ||Nw.d ||N8.1 ||000123.4 || |
Generally, string data uses the string format (`Aw` where `w` is the field width) for displaying data. See [[SPSS/DataFormats#Print_Formats|here]] for further information. |
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| ---- | See [[SPSS/StringFunctions|here]] for the built-in library of string functions. |
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| == Strings == | === String Literals === |
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| String variables are only formatted to a length. The format is specified as `AN` where `N` is the width. | String literals are declared by wrapping a string value in quotes, either single (`'`) or double (`"`). Quote marks within strings can be handled in one of two ways: either use the opposite quote mark to wrap the string, or escape the quote mark by doubling it. {{{ variable label var1 "Say ""Hello!""". variable label var2 'Don''t say "Goodbye!"'. }}} |
SPSS Data Types
SPSS exposes numeric and string data types.
Certain specialized forms of data are handled by formats that impact visualization and export, not storage. The primary example of this is date and time data.
Numeric Data
Numeric data is stored as double-precision floating point.
Generally, numeric data uses either a numeric format (Fw.d where w is the field width and d is the number of visible decimal places) or a restricted numeric format (Nw) for displaying data. See here for further information. The default format, which will be applied to any implicitly declared variables, is F8.2.
Date and Time Data
Dates are stored as the number of seconds from midnight, October 14, 1582 to midnight on the specified date. Generally the DATE10 format is used for displaying data.
Datetimes are stored as the number of seconds to the specified time on the specified date. Generally the DATETIME20 format is used for displaying data.
Times are stored as the number of seconds. This can be imagined as the number of seconds from midnight to the specified time, but that is not a necessary construct. Generally the TIME8 format is used for displaying data.
Keep in mind that 1 day = 60 (seconds) * 60 (minutes) * 24 (hours) = 86400 seconds.
For more information about date and time formats, see here.
See here for the built-in library of date and time functions.
String Data
String data is stored at a fixed length.
A string variable can only be explicitly declared, as by the STRING command.
Generally, string data uses the string format (Aw where w is the field width) for displaying data. See here for further information.
See here for the built-in library of string functions.
String Literals
String literals are declared by wrapping a string value in quotes, either single (') or double (").
Quote marks within strings can be handled in one of two ways: either use the opposite quote mark to wrap the string, or escape the quote mark by doubling it.
variable label var1 "Say ""Hello!""". variable label var2 'Don''t say "Goodbye!"'.