Compare two datasets --------------------
^cf3^ varlist ^using^ filename ^, id(^varname^)^ [^nov^erbose]
^cf3^ is a variation on ^cf^ and ^cf2^ that matches observations by a record id > variable and lists the observations where differences exist. Like ^cf^ and ^cf > 2^, ^cf3^ compares variables of the dataset in memory (the 'master' data) to the corresponding variables in a file (the 'using' data). The variables to be compared are specified in varlist. Alternatively, ^_all^ may be specified to request that all variables be compared. ^cf3^ returns 0 if the specified variables are identical and 9 if there are any differences. Only the variable values are compared. Variable labels, value labels, notes, characteristics, etc. are not compared.
^cf3^ also differs from ^cf^ (and from ^cf2^, if installed) in that: 1) the ^id > ()^ option, which names the common record id variable in each file, is required; 2) ^verbose^ is presumed but option ^noverbose^ will suppress some output; and 3) it will not stop if there is a differing number of observations in the two files. Generally, the id variable values should be unique within each file. If the id values are not unique then proper matching may not occur; ^cf3^ will warn the user but will continue. Incorrectly-matched observations, where the variables being compared also differ, and unmatched observations will be reported as differences.
In the listings, variable names given for the 'using' dataset are a slight modification of the actual variable names. If necessary, they are truncated to 7 characters, and all are preceded by an underscore character.
^id(^varname^)^ is a required option that specifies the record id variable within the datasets. This id is displayed as part of the output.
^noverbose^ suppresses the detailed listing of observations where differences exist in each variable. If specified, only the number of differences will be mentioned.
. ^cf3 mpg weight displ using mydata, id(make)^
. ^cf3 _all using mydata, id(make) noverbose^
Also see --------
Manual: ^[R] cf^ On-line: help for @cf@; @compare@; @cf2@ (if installed)