Description Details Author(s) See Also Examples
QueryResult is a reference class that enables paging through query results.
Synapse has the ability to query for entities using a SQL-like query language. See the Query service API wiki for details on how to form a query: http://sagebionetworks.jira.com/wiki/display/PLFM/Repository+Service+API#RepositoryServiceAPI-QueryAPI
The QueryResult object is returned from the synapseQuery function when blockSize
is specified. The
client can then call either fetch()
or collect()
to get the next block of results as a data.frame.
The difference is that with collect()
, the results are accumulated. For example, after 3 calls to collect()
,
with a blockSize
of 10 we would expect a data.frame with 30 rows.
The collectAll()
method repeatedly requests blocks of blocksize
query results until there are no more or the
limit is reached. This can be slow, so use with caution. It's usually safer to set a limit.
J. Christopher Bare <chris.bare@sagebase.org>
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | ## Not run:
## get a QueryResult object back from a query
qr <- synapseQuery("select id, name, parentId from file limit 1000", blockSize=100)
## get a data.frame with 100 results
df <- qr$fetch()
## accumulate the next 300 results
df <- qr$collect()
df <- qr$collect()
df <- qr$collect()
# get number of rows accumulated
# should be 400 with initial fetch plus 3 calls to collect
length(qr)
# return the selected column names
names(qr)
## accumulate the remaining results.
## df will be a data.frame with all 1000 accumulated rows
df <- qr$collectAll()
## End(Not run)
|
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.