Databases
StackOverflow2013
Postsdbo
POExtract values from an array in mongoDB to dataframe using rmongodb
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POExtract values from an array in mongoDB to dataframe using rmongodb
    primarykey
    data
    text
    <p>I'm querying a database containing entries as displayed in the example. All entries contain the following values:</p> <ul> <li><code>_id</code>: unique id of <code>overallitem</code> and <code>placed_items</code></li> <li><code>name</code>: the name of te <code>overallitem</code></li> <li><code>loc</code>: location of the <code>overallitem</code> and <code>placed_items</code></li> <li><code>time_id</code>: time the <code>overallitem</code> was stored</li> <li><code>placed_items</code>: array containing <code>placed_items</code> (can range from zero: <code>placed_items : [],</code> to unlimited amount. </li> <li><code>category_id</code>: the category of the <code>placed_items</code></li> <li><code>full_id</code>: the full id of the <code>placed_items</code></li> </ul> <p>I want to extract the <code>name</code>, <code>full_id</code> and <code>category_id</code> on a per <code>placed_items</code> level given a <code>time_id</code> and <code>loc</code> constraint</p> <p>Example data:</p> <pre><code>{ "_id" : "5040", "name" : "entry1", "loc" : 1, "time_id" : 20121001, "placed_items" : [], } { "_id" : "5041", "name" : "entry2", "loc" : 1, "time_id" : 20121001, "placed_items" : [ { "_id" : "5043", "category_id" : 101, "full_id" : 901, }, { "_id" : "5044", "category_id" : 102, "full_id" : 902, } ], } { "_id" : "5042", "name" : "entry3", "loc" : 1, "time_id" : 20121001, "placed_items" : [ { "_id" : "5045", "category_id" : 101, "full_id" : 903, }, ], } </code></pre> <p>The expected outcome for this example would be:</p> <pre><code>"name" "full_id" "category_id" "entry2" 901 101 "entry2" 902 102 "entry3" 903 101 </code></pre> <p>So if <code>placed_items</code> is empty, do put the entry in the dataframe and if <code>placed_items</code> containts <code>n</code> entries, put <code>n</code> entries in dataframe</p> <p>I tried to work out an RBlogger example to create the desired dataframe. </p> <pre><code>#Set up database mongo &lt;- mongo.create() #Set up condition buf &lt;- mongo.bson.buffer.create() mongo.bson.buffer.append(buf, "loc", 1) mongo.bson.buffer.start.object(buf, "time_id") mongo.bson.buffer.append(buf, "$gte", 20120930) mongo.bson.buffer.append(buf, "$lte", 20121002) mongo.bson.buffer.finish.object(buf) query &lt;- mongo.bson.from.buffer(buf) #Count count &lt;- mongo.count(mongo, "items_test.overallitem", query) #Note that these counts don't work, since the count should be based on #the number of placed_items in the array, and not the number of entries. #Setup Cursor cursor &lt;- mongo.find(mongo, "items_test.overallitem", query) #Create vectors, which will be filled by the while loop name &lt;- vector("character", count) full_id&lt;- vector("character", count) category_id&lt;- vector("character", count) i &lt;- 1 #Fill vectors while (mongo.cursor.next(cursor)) { b &lt;- mongo.cursor.value(cursor) order_id[i] &lt;- mongo.bson.value(b, "name") product_id[i] &lt;- mongo.bson.value(b, "placed_items.full_id") category_id[i] &lt;- mongo.bson.value(b, "placed_items.category_id") i &lt;- i + 1 } #Convert to dataframe results &lt;- as.data.frame(list(name=name, full_id=full_uid, category_id=category_id)) </code></pre> <p>The conditions work and the code works if I would want to extract values on an <code>overallitem</code> level (i.e. <code>_id</code> or <code>name</code>) but fails to gather the information on a <code>placed_items</code> level. Furthermore, the dotted call for extracting <code>full_id</code> and <code>category_id</code> does not seem to work. Can anyone help?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USMax van der Heijden
    1. USMax van der Heijden
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. POExtract values from an array in mongoDB to dataframe using rmongodb
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POExtract values from an array in mongoDB to dataframe using rmongodb
      1. USSCallan
      1. VTFavorite
    1. COWhat version of MongoDB are you using?
      singulars
      1. POExtract values from an array in mongoDB to dataframe using rmongodb
      1. USStennie
    2. CO@Stennie Version 2.2
      singulars
      1. POExtract values from an array in mongoDB to dataframe using rmongodb
      1. USMax van der Heijden
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload