SAS - Unzip all .gz files in a folder - sas

Question

SAS Program - I am trying to unzip all .gz type files in a folder and reading them to a dataset using filename statement. However, I am not able to make it work.
I have .gz files named as follows in a folder:
EQY_US_ALL_TRADE_20210701
EQY_US_ALL_TRADE_20210702
EQY_US_ALL_TRADE_20210705
EQY_US_ALL_TRADE_20210706
EQY_US_ALL_TRADE_20210707
.....
.....
EQY_US_ALL_TRADE_20210729
EQY_US_ALL_TRADE_20210730
so on.
Note that it does NOT have files for all 31 days in a folder - files are only for business days.
See my code below:
/* Change working directory to where all the files are located */
data _null_;
rc=dlgcdir("C:\EQY_US_ALL_TRADE_202107");
put rc=;
run;
/* using filename statement unzip all files and read them into "f1" */
filename f1 zip EQY_US_ALL_TRADE_202107* gzip lrecl=500;
/* This code worked when I had the actual name of one of the file - for e.g. "EQY_US_ALL_TRADE_20210702" but does not work when I use the wildcard to run through all of them */

Answer 1

You can read the file names in the folder using the DREAD function, and then a dynamic INFILE statement using the FILEVAR= option to specify the gunzip stream that will be INPUTed from.
Example:
All gzipped files are presumed to be data only and do not contain a header row. The compressed files are all in a single folder and have the .gz file extension
data want(keep=filename a b c);
length folderef $8;
rc = filename (folderef, 'c:\temp\trade_data');
did = dopen(folderef);
do _n_ = 1 to dnum(did);
filename = dread(did,_n_);
if scan(filename,-1,'.') ne 'gz' then continue;
fullname = pathname(folderef) || '/' || filename;
do while(1);
infile archive zip filevar=fullname gzip dlm=',' eof=nextfile;
input a b c;
OUTPUT;
end;
nextfile:
end;
stop;
run;