-if_rec¶

Introduction¶

The -if_rec option is an -if for a range of record numbers. The -if_rec option uses the same syntax as the "for" option. If you want to operate on records 10 to 20, you would use the parameter 10:20. If you want to operate on all the even records from 10 to 20, you would use 10:20:2. The restrictions are the start value must be less than the ending value and the step has to be greater than zero.

The -if_rec option is similar to the -for option in that they both select a range of records. The difference is that the -for option selects the range of records that wgrib2 will process. With the the -if_rec option, all the records will be processed but only the additional processing within the -if block will be only done for the selected records. The -for option can be much faster if the field has to be decoded. With the -for option, only the selected records need to be docoded whereas all the records would be decoded when using the -if_rec option. The command line, however, can have multiple -if_rec options.

Usage¶

-if_rec I:J:K        same as for n = I to J by K
-if_rec I:J          same as for n = I to J by 1
-if_rec I::K         same as for n = I to MAX_INTEGER by K
-if_rec I            same as for n = I to MAX_INTEGER by 1

Example¶

 $ wgrib2 file.grb2 -if\_rec 4:5 -s -fi
4:13335:d=2008120200:RH:750 mb:anl:
5:17098:d=2008120200:TMP:2743 m above mean sea level:anl: