The documents are returned sorted on relevance depending on order, proximity, frequency of terms.
Default search behavior
By default, all search terms are optional. It behaves like an OR logic. Objects that contain the more terms are rated higher in the results and will appear first in their type. For example, wiki forum will find:
- objects that include both terms
- objects that include the term wiki
- objects that include the term forum
Requiring terms
Add a plus sign ( + ) before a term to indicate that the term must appear in results. Example: +wiki forum will find objects containing at least wiki. Objects with both terms and many occurences of the terms will appear first.
Excluding terms
Add a minus sign ( - ) before a term to indicate that the term must not appear in the results. To reduce a term's value without completely excluding it, use a tilde. Example: -wiki forum will find objects that do not contain wiki but contain forum
Grouping terms
Use parenthesis ( ) to group terms into subexpressions. Example: +wiki +(forum blog) will find objects that contain wiki and forum or that contain wiki and blog in any order.
Finding phrases
Use double quotes ( " " ) around a phrase to find terms in the exact order, exactly as typed. Example: "Alex Bell" will not find Bell Alex or Alex G. Bell.
Using wildcards
Add an asterisk ( * ) after a term to find objects that include the root word. For example, run* will find:
- objects that include the term run
- objects that include the term runner
- objects that include the term running
Reducing a term's value
Add a tilde ( ~ ) before a term to reduce its value indicate to the ranking of the results. Objects that contain the term will appear lower than other objects (unlike the minus sign which will completely exclude a term). Example: +wiki ~forum will rate an object with only wiki higher that an object with wiki and forum.
Changing relevance value
Add a less than ( < ) or greater than ( > ) sign before a term to change the term's contribution to the overall relevance value assigned to a object. Example: +wiki +(>forum < blog) will find objects that contain wiki and forum or wiki and blog in any order. wiki forum will be rated higher.
Full access via SW toolset
Current SAFE toolset provides access to product metadata but it is needed to develop product specific software tools to handle data files. It would be useful that the infrastructure provides a guaranteed resource to access the information inside a SAFE product
- product subsetting: given a time interval or a polygon inside the product spatio-temporal coverage(complete SAFE product with part of the binary data)
- complete access to the product data (data variable listing, description, value extraction)
- metadata extraction
- browse extraction
All the measurement contained in the data component of a SAFE product should be clearly recognizable. Currently the meaning and unit of measure of the variable in a data file are only described by a textual description in the data schema.
Thus, the following considerations shall be needed to be defined for a full access via the toolset:
- Formal description of the data variable contained in a SAFE product (dimensions, unit of measure, range, special values (e.g. no measurement or saturated) and any other attribute needed for the complete understanding of the information reported (e.g. star name for limb looking sensor)
- Conventions for data variable name in order to give data variable an homogeneous and clear semantic meaning (e.g. as done in CF-NetCDF)