static bool TryReadTimePrecision(ref feather.fbs.Column column, out DateTimePrecisionType precision, out string errorMessage)
{
var metadata = column.Metadata <TimeMetadata>();
if (metadata == null)
{
precision = default(DateTimePrecisionType);
errorMessage = $"Couldn't read Precision for column {column.Name}, no TimeMetadata";
return(false);
}
var metadataValue = metadata.Value;
var unit = metadataValue.Unit;
switch (unit)
{
case TimeUnit.MICROSECOND: precision = DateTimePrecisionType.Microsecond; break;
case TimeUnit.MILLISECOND: precision = DateTimePrecisionType.Millisecond; break;
case TimeUnit.NANOSECOND: precision = DateTimePrecisionType.Nanosecond; break;
case TimeUnit.SECOND: precision = DateTimePrecisionType.Second; break;
default:
precision = default(DateTimePrecisionType);
errorMessage = $"Couldn't understand TimeUnit {unit}";
return(false);
}
errorMessage = null;
return(true);
}
static bool TryReadTimestampPrecision(ref feather.fbs.Column column, out DateTimePrecisionType precision, out string errorMessage)
{
var metadata = column.Metadata <TimestampMetadata>();
if (metadata == null)
{
precision = default(DateTimePrecisionType);
errorMessage = $"Couldn't read Precision for column {column.Name}, no TimestampMetadada";
return(false);
}
var metadataValue = metadata.Value;
var timezoneName = metadataValue.Timezone;
var unit = metadataValue.Unit;
// note: supporting other timezones would be nice,
// but the timezone included appears to just be
// a passthrough from as.POSIXct (in R anyway)
// which lets a bunch of ambiguous junk through
// (timezone abbreviations are NOT unique, or
// properly spec'd even).
// the only thing we can rely on being the same
// everywhere is UTC, so constrain to that.
var isntUtc =
timezoneName != null &&
!timezoneName.Equals("UTC", StringComparison.InvariantCultureIgnoreCase) &&
!timezoneName.Equals("GMT", StringComparison.InvariantCultureIgnoreCase);
if (isntUtc)
{
errorMessage = $"Cannot read Timestamp in timezone {timezoneName}, only UTC/GMT is supported";
precision = default(DateTimePrecisionType);
return(false);
}
switch (unit)
{
case TimeUnit.MICROSECOND: precision = DateTimePrecisionType.Microsecond; break;
case TimeUnit.MILLISECOND: precision = DateTimePrecisionType.Millisecond; break;
case TimeUnit.NANOSECOND: precision = DateTimePrecisionType.Nanosecond; break;
case TimeUnit.SECOND: precision = DateTimePrecisionType.Second; break;
default:
precision = default(DateTimePrecisionType);
errorMessage = $"Couldn't understand TimeUnit {unit}";
return(false);
}
errorMessage = null;
return(true);
}
static bool TryReadCategoryLevels(MemoryMappedViewAccessor view, ref feather.fbs.Column column, out string[] categoryLevels, out string errorMessage)
{
var metadata = column.Metadata <CategoryMetadata>();
if (metadata == null)
{
categoryLevels = null;
errorMessage = $"Couldn't read Category levels for column {column.Name}, no CategoryMetadata";
return(false);
}
var metadataValue = metadata.Value;
if (metadataValue.Levels == null)
{
categoryLevels = null;
errorMessage = $"Couldn't read Category levels for column {column.Name}, no Levels";
return(false);
}
var levels = metadataValue.Levels.Value;
if (levels.Type != feather.fbs.Type.UTF8)
{
categoryLevels = null;
errorMessage = $"Found non-string ({levels.Type}) for column {column.Name}";
return(false);
}
ColumnSpec categoryColumn;
if (!TryMakeColumnSpec(nameof(TryReadCategoryLevels) + "__FAKE__", levels.Type, ref levels, null, default(DateTimePrecisionType), out categoryColumn, out errorMessage))
{
categoryLevels = null;
return(false);
}
categoryLevels = new string[levels.Length];
for (var i = 0; i < levels.Length; i++)
{
var categoryName = DataFrame.ReadString(view, levels.Length, null, ref categoryColumn, i);
categoryLevels[i] = categoryName;
}
errorMessage = null;
return(true);
}