STEM help

1.3.3 How to refine a search expression

To search for one or more terms in the online STEM help pages, simply enter them into the search box separated by spaces and then hit return or click the Search button. This will find any pages that match any of the terms. For more complex search queries you can use the syntax described below.

Specify where to search

You can specify that a term should be searched for only in the body text or title of each page by prefixing body: or title: to a term. For example, to search for pages that have Consolidation in the title you would use title:Consolidation.

Search for a phrase

You can search for a phrase rather than individual terms by enclosing the phrase in quote marks: e.g., you might search for "shorter time periods".

AND operator

By default, a search for a number of terms will match pages with any of those terms in them. If instead you want to make a search for pages that match all of a given set of terms then you can combine terms with the operator AND. For example, to search for pages that contain the words Erlang and result you would enter Erlang AND result.

You can combine this with a regular ‘or’ search by surrounding the AND terms with brackets. So, if you wanted to search for all pages that have the words results and defining in them together, or that have the single term cnf you could use the query (results AND defining) cnf.

Requiring matches

If you are searching for multiple terms, by default you will be shown pages that mention any of those terms. If you only want to see pages that include one (or more) of those terms, you can preceed the term that must be present with +. For example, if you want to be shown only the pages that contain both the words time and series, you could use the search query +time +series. Including other terms without the + will alter the ordering of results but will not give you any new results: for example, the query +time +series numeric would find the same pages as the first example, but pages containing the word numeric would appear higher on the results page.

Excluding matches

Rather than specifying a term to look for, you can specify that you do not want to see pages that match a given term. This may only be done in combination with another term or terms – you can’t just search for every page that doesn’t mention a given word. For example, to search for all pages that contain the word time but that don’t contain the word series you could enter time -series.

Wildcards

The search function understands two symbols that can match any text. You can use * to match any text of any length (including zero length), and ? to match any single character. These can be used within a term or at the end of a term, but not at the start of a term. For example, you might want to match against administration, administrative and the abbreviation admin. To do this with a single term you can search for admin*, whereas to make this also match against admonish you could search for adm?n*.

Wildcards will not match against spaces (e.g., dem*nd will match demand but won’t match demonstrate and).

Fuzzy matching

If you want to search for several very similar words or if you want to cope with spelling variations you can specify a fuzzy match by adding ~ to the end of the search term. For example, if you search for color~ this will still match against pages mentioning the UK spelling colour as well. You can add a number between 0 and 1 after the ~ to indicate how close a match you are looking for. For example, the search term color~0.1 will match against a wide range of quite different words, whereas color~0.9 will match only terms that quite closely correspond to color. If you don’t specify a number for the match precision you will by default get the results for a search with 0.5 specified.

You can also perform fuzzy matching for phrases. In this case you match against the exact spelling of each word within a phrase, but you allow that the phrase may have extra words inserted into it or be reordered. To do this, use the same ~ operator after your phrase, and follow it with a number indicating how many other words may separate the words in the phrase that you are looking for. A change in ordering of the words counts as a separation of one place. For example, to search for any page that has the phrase time period but to also catch similar phrases like period of time or time in a period, you could enter "time period"~2 into the search box.

Importance boosting

It is possible to tell the search engine that some of your terms are more important than others when determining the relevance of a document. You can do this by adding the ^ operator after a search term, followed by a number indicating how much to multiply the importance of that term by. For example, to search for all documents that contain the words connection or tariff but to ensure that pages that mention connection are considered as three times more important when deciding the order in which results are presented, you can search for connection^3.0 tariff.

Understand stemming

The search engine reduces each term that you enter to a stem, and it does the same for the content being searched. This is done on the assumption that if you are searching, for example, for chart you are probably also interested in pages that mention charts, charting or charted. However, this stemming process relies upon natural language processing and is unlikely to be 100% reliable. If you think you are missing results, it may be worth using a wildcard search as described above to ensure you catch word variations.

Avoid special symbols

As this page describes, several symbols have special meaning when used in a search query. Your search will not work well if you include any of these symbols in your query. The best you can do to match these is to use a wildcard character (?) instead, but be aware that due to the way we build our search index you are unlikely to see any matches for terms containing these symbols anyway.

The symbols that must be avoided in this way are: + - & | ! ( ) { } [ ] ^ " ~ * ? : \

Combining rules

You may combine any of the rules described above in a single query. For example, to search for pages that have the phrase results workspaces in their main (body) content and that have the word graph in their title, you might enter body:"results workspaces" AND title:graph.

 

Help on help

The STEM help system has been designed and structured to make it easy to find the information you want. The organisation of the help system is described in detail too.

Read more

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