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Sets key/value pairs in the input grib GRIB file and writes each message to the output_grib_file. It fails when an error occurs (e.g. key not found).
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Where clause. Set is only executed for grib GRIB messages matching all the key/value constraints. If a grib GRIB message does not match the constraints it is copied unchanged to the output_grib_file. This behaviour can be changed setting the option -S. A valid constraint is of type key=value or key!=value. For each key a string (key:s), a double (key:d) or an integer (key:i) type can be defined. Default type is string. In the value you can also use the forward-slash character '/' to specify an OR condition (i.e. a logical disjunction) Note: only one -w clause is allowed.
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Multi-field support off. Turn off support for multiple fields in single grib GRIB message.
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Copy GTS header.
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GRIBEX compatibility mode.
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To set productDefinitionTemplateNumber=2 only for the fields with productDefinitionTemplateNumber=11
Code Block > grib_set -s productDefinitionTemplateNumber=2 -w productDefinitionTemplateNumber=11 ../data/tigge_pf_ecmwf.grib2 out.grib2
To set productDefinitionTemplateNumber=2 only for the fields for which productDefinitionTemplateNumber is not equal to 11
Code Block > grib_set -s productDefinitionTemplateNumber=2 -w productDefinitionTemplateNumber!=11 tigge_pf_ecmwf.grib2 out.grib2
When a key is not used all the bits of its value should be set to 1 to indicate that it is missing. Since the length (number of octet) is different from a key to another, the value that we have to code for missing keys is not unique. To give an easy way to set a key to missing a string "missing" or "MISSING" is accepted by grib_set as follows:
Since some values can not be set to missing you can get an error for those keys.Code Block > grib_set -s scaleFactorOfFirstFixedSurface=missing,scaledValueOfFirstFixedSurface=MISSING ../data/regular_latlon_surface.grib2 out.grib2
To set scaleFactorOfSecondFixedSurface to missing only for the fields for which scaleFactorOfSecondFixedSurface is not missing:
Code Block > grib_set -s scaleFactorOfSecondFixedSurface=missing -w scaleFactorOfSecondFixedSurface!=missing tigge_pf_ecmwf.grib2 out.grib2
It 's is possible to produce a grib GRIB edition 2 file from a grib GRIB edition 1 by just changing the edition number with grib_set. However it is important that you carefully inspect the output and check the information is correctly translated.
For more details please see: GRIB: Converting edition 1 toCode Block grib_set -s edition=2 ../data/reduced_gaussian_pressure_level.grib1 out.grib2
https://software.ecmwf.int/wiki/display/ECC/GRIB%3A+Converting+edition+1+to+2
With grib edition 2 is possible to compress data using the jpeg algorithm. To change packing algorithm from grid_simple (simple packing) to grid_jpeg (jpeg2000 packing):
Code Block > grib_set -s packingType=grid_jpeg ../data/regular_gaussian_model_level.grib2 out.grib2
It's possible to ask ecCodes to calculate the number of bits per value needed to pack a given field with a fixed number of decimal digits of precision. For example if we want to pack a temperature expressed in Kelvin with 1 digits of precision after the decimal point we can set changeDecimalPrecision=1
Code Block > grib_set -s changeDecimalPrecision=1 ../data/regular_latlon_surface.grib2 ../data/out.grib2