Track Database Definition

NOT FOR HUBS. Not yet supported by bigBeds

Another method of filtering items relies upon discrete values. One or more fields such as name or score may contain a limited number of discrete values that can be filtered on. These discrete values will be displayed in a dropdown list from which the user can choose one or more options. While the maximum number of options in the list is not limited, displaying too many options can be confusing for the user.

Setting complexities:

• Because filters for different fields are delimited by whitespace, any whitespace in titles and labels should be replaced by the '_' (underscore) character.
• Each field/option pair is joined by '=' (equal sign).
• The field portion can have a title that is delimited from the field name by ': (colon)'.
• A single field filter will have multiple options delimited by commas.
• If the options are a 1-based index (1,2,3...) then the option list can be preceded with a '+' (plus sign) and the options themselves are only labels.
• Otherwise, each option will be a value and optional label delimited by '|' (vertical bar). Note that if one option has a label then all options of that filter must have a label.
• Finally, options may have CSS style wrapped in {curly} brackets and appended to the end.

Because of this complexity, please remember to use the '\' continuation line to ensure the setting is readable:

    filterBy {field1}[:{Title1}]=[+]\
             option1a[|label1a[{style1a}]],\
             option1b[|label1b[{style1b}]],... \
             [{field2}[:{Title2}]=[+]\
             option2a[|label2a[{style2a}]],,...]    

It is probable that this setting will be redefined at some point, given that it is very complicated. However, this current format will be supported until entirely replaced.

The best way to understand this setting is with an example. This is an operational example in the hg19 "Open Chrom Synth" track.

Example:

    filterBy color:Validation_Level=\
             0|Validated_(OC_1){color:#000000},\
             255|Open_Chromatin_(OC_2-3){color:#0000FF},\
             39168|DNase_low_(OC_2){color:#009900},\
             10027008|FAIRE_low_(OC_3){color:#990000},\
             16711935|ChIP-seq_(OC_4){color:#FF00FF} \
             ocCode:OC_Code=+\
             One:_Validated_(all),\
             Two:_DNase_(all),\
             Three:_FAIRE_(all),\
             Four:_ChIP_(all)    

This setting sets up two filters, one on the field "color" and a second for the "ocCode" field. The color filter is given the title "Validation Level". The second option has a value of "255" and a label of "Open Chromatin (OC 2-3)". Note that it will appear as blue in the list due to the {color:#0000FF} style definition. Also notice that all options for this color field have a style defined, even though the first option is black and would be so by default. In this example, the only whitespace within the setting value section immediately precedes the second filter definition. The second filter, "ocCode", is titled by the inscrutable "OC Code". It is a numeric index filter (as declared by the '+'). The value of the second option is 2 and only the label gets defined as "Two: Dnase (all)". Note that the colon in the label is an HTML code.

The filterBy setting is very powerful. We recommend that you experiment with the settings to determine which work best for your case.