Class: VDataFrame

VDataFrame(buckets, series, signalFilteropt, columnExpandModeopt, signalQueueModeopt)

A class for two-dimensional tabular data frame that holds signal time-values. Column names can be accessed via method cols(), and signal time-values can be accessed through methods values(), objects(), sampling(), object1s depending on the usage scenario. Examples: let reader = factory.open(); let frame = reader.df(); let cols = frame.cols(true); let values = frame.objects();

Constructor

new VDataFrame(buckets, series, signalFilteropt, columnExpandModeopt, signalQueueModeopt)

The constructor for the data frame. It is called via VDataReader.
Parameters:
Name Type Attributes Default Description
buckets Array.<VDataBucket> the list of buckets
series Map the map of signal series
signalFilter VDataSignalFilter <optional>
 null the signal filter
columnExpandMode string <optional>
 null the column expand mode
signalQueueMode string <optional>
 null the signal queue mode

Methods

cols(includeTimeopt) → {Array.<string>}

Get a list of column names. The order of the column names is same as order of signal values in each row. To include the time column at first index set the includeTime parameter to true.
Parameters:
Name Type Attributes Default Description
includeTime boolean <optional>
 false whether to include time column at first index
Returns:
array of column names
Type
Array.<string>

getColumnExpandMode() → {number}

Get the column expand mode for expanding complex type.
Returns:
Type
number

getColumnExpandMode() → {string}

Get the signal queue mode for value triage when there are multiple values at the same time.
Returns:
Type
string

getEndTime() → {number}

Get the last time of signals in the frame. Note that this time may be the evenly-split end time of the last bucket and slightly different from the actual last signal time.
Returns:
millisecond since EPOCH
Type
number

getSignalFilter() → {VDataSignalFilter}

Get the signal filter.
Returns:
Type
VDataSignalFilter

getStartTime() → {number}

Get the earliest time of signals in the frame. Note that this time may be the evenly-split start time of the first bucket and slightly different from the actual first signal time.
Returns:
millisecond since EPOCH
Type
number

object1s() → {Array.<Object>}

Return a sorted 2-d array (row-columns) of all data objects at the sampled 1-Hz interval. The first item of each row is time, followed by values.
Returns:
Type
Array.<Object>

objects(densifyRowsAheadopt, densifyOutputItvopt) → {Array.<Object>}

Get a sorted 2-d array (row-columns) of time and all data values. The values are read all into memory and avoid sorting. It is CPU-efficient but consumes more memory. Therefore, this method is suitable for reading data files smaller than 10MB. The first item of each row is time, followed by values.
Parameters:
Name Type Attributes Default Description
densifyRowsAhead * <optional>
 0 number of rows to look ahead to fill sparse data
densifyOutputItv * <optional>
 0 millis interval to down-sample data
Returns:
Type
Array.<Object>

sampling(frequency) → {Array.<Object>}

Return a sorted 2-d array (row-columns) of all data objects sampled down to the specified frequency in milliseconds. For example, 1-Hz equals a frequency of 1000 (ms). The first item of each row is time, followed by values.
Parameters:
Name Type Description
frequency number the sampled frequency with value greater than 1
Returns:
Type
Array.<Object>

series() → {Map}

Get a map of all selected signal series.
Returns:
map of series by their names
Type
Map

setColumnExpandMode(mode)

Set the column expand mode for expanding complex type.
Parameters:
Name Type Description
mode number the expand mode

setEndTime(time)

Set the end time of the frame.
Parameters:
Name Type Description
time number millisecond since EPOCH

setSignalFilter(signalFilter)

Set the signal filter.
Parameters:
Name Type Description
signalFilter VDataSignalFilter the filter

setSignalQueueMode(mode)

Set the signal queue mode for value triage when there are multiple values at the same time.
Parameters:
Name Type Description
mode string the queue mode

setStartTime(time)

Set the start time of the frame.
Parameters:
Name Type Description
time number millisecond since EPOCH

values(densifyRowsAheadopt, densifyOutputItvopt, signalQueueRowsopt) → {Array.<Object>}

Get a sorted 2-d array (row-columns) of time and all data values. The values are read via a iterator-like processing which is more memory-efficient but consumes more CPU. Therefore, this method is suitable for reading data files larger than 10MB. The first item of each row is time, followed by values.
Parameters:
Name Type Attributes Default Description
densifyRowsAhead * <optional>
 0 number of rows to look ahead to fill sparse data
densifyOutputItv * <optional>
 0 millis interval to down-sample data
signalQueueRows * <optional>
 0 number of rows to hold in queue for sorting
Returns:
Type
Array.<Object>