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92 lines
2.5 KiB
SAS
92 lines
2.5 KiB
SAS
/**
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@file
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@brief Returns a unique hash for a dataset
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@details Ignores metadata attributes, used only to hash values. If used to
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compare datasets, they must have their columns and rows in the same order.
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%mp_hashdataset(sashelp.class,outds=myhash)
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data _null_;
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set work.myhash;
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put hashkey=;
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run;
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<h4> SAS Macros </h4>
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@li mf_getattrn.sas
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@li mf_getuniquename.sas
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@li mf_getvarlist.sas
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@li mp_md5.sas
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<h4> Related Files </h4>
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@li mp_hashdataset.test.sas
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@li mp_hashdirectory.sas
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@param [in] libds dataset to hash
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@param [in] salt= Provide a salt (could be, for instance, the dataset name)
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@param [in] iftrue= (1=1) A condition under which the macro should be executed
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@param [out] outds= (work._data_) The output dataset to create. This
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will contain one column (hashkey) with one observation (a $hex32.
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representation of the input hash)
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|hashkey:$32.|
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|---|
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|28ABC74ABFC45F50794237BA5566E6CA|
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@version 9.2
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@author Allan Bowe
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**/
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%macro mp_hashdataset(
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libds,
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outds=work._data_,
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salt=,
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iftrue=%str(1=1)
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)/*/STORE SOURCE*/;
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%local keyvar /* roll up the md5 */
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prevkeyvar /* retain prev record md5 */
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lastvar /* last var in input ds */
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cvars nvars;
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%if not(%eval(%unquote(&iftrue))) %then %return;
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/* avoid naming conflict for hash key vars */
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%let keyvar=%mf_getuniquename();
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%let prevkeyvar=%mf_getuniquename();
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%let lastvar=%mf_getuniquename();
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%if %mf_getattrn(&libds,NLOBS)=0 %then %do;
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data &outds;
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length hashkey $32;
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hashkey=put(md5("&salt"),$hex32.);
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output;
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stop;
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run;
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%put &sysmacroname: Dataset &libds is empty, or is not a dataset;
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%put &sysmacroname: hashkey of &outds is based on salt (&salt) only;
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%end;
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%else %if %mf_getattrn(&libds,NLOBS)<0 %then %do;
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%put %str(ERR)OR: Dataset &libds is not a dataset;
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%end;
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%else %do;
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data &outds(rename=(&keyvar=hashkey) keep=&keyvar)
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%if "%substr(&sysver,1,1)" ne "4" and "%substr(&sysver,1,1)" ne "5" %then %do;
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/nonote2err
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%end;
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;
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length &prevkeyvar &keyvar $32;
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retain &prevkeyvar;
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if _n_=1 then &prevkeyvar=put(md5("&salt"),$hex32.);
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set &libds end=&lastvar;
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/* hash should include previous row */
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&keyvar=%mp_md5(
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cvars=%mf_getvarlist(&libds,typefilter=C) &prevkeyvar,
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nvars=%mf_getvarlist(&libds,typefilter=N)
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);
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&prevkeyvar=&keyvar;
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if &lastvar then output;
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run;
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%end;
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%mend mp_hashdataset;
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