// This method is called if only a datafile is specified, without a loader/term and value columns.
// It determines the type of the Value column and returns the appropriate TextLoader component factory.
private static IComponentFactory <IMultiStreamSource, IDataLoader> GetLoaderFactory(string filename, bool keyValues, IHost host)
{
Contracts.AssertValue(host);
// If the user specified non-key values, we define the value column to be numeric.
if (!keyValues)
{
return(ComponentFactoryUtils.CreateFromFunction <IMultiStreamSource, IDataLoader>(
(env, files) => new TextLoader(
env,
new TextLoader.Arguments()
{
Column = new[]
{
new TextLoader.Column("Term", DataKind.TX, 0),
new TextLoader.Column("Value", DataKind.Num, 1)
}
},
files)));
}
// If the user specified key values, we scan the values to determine the range of the key type.
ulong min = ulong.MaxValue;
ulong max = ulong.MinValue;
try
{
var txtArgs = new TextLoader.Arguments();
bool parsed = CmdParser.ParseArguments(host, "col=Term:TX:0 col=Value:TX:1", txtArgs);
host.Assert(parsed);
var txtLoader = new TextLoader(host, txtArgs, new MultiFileSource(filename));
using (var cursor = txtLoader.GetRowCursor(c => true))
{
var getTerm = cursor.GetGetter <DvText>(0);
var getVal = cursor.GetGetter <DvText>(1);
DvText txt = default(DvText);
using (var ch = host.Start("Creating Text Lookup Loader"))
{
long countNonKeys = 0;
while (cursor.MoveNext())
{
getVal(ref txt);
ulong res;
// Try to parse the text as a key value between 1 and ulong.MaxValue. If this succeeds and res>0,
// we update max and min accordingly. If res==0 it means the value is missing, in which case we ignore it for
// computing max and min.
if (Conversions.Instance.TryParseKey(ref txt, 1, ulong.MaxValue, out res))
{
if (res < min && res != 0)
{
min = res;
}
if (res > max)
{
max = res;
}
}
// If parsing as key did not succeed, the value can still be 0, so we try parsing it as a ulong. If it succeeds,
// then the value is 0, and we update min accordingly.
else if (Conversions.Instance.TryParse(ref txt, out res))
{
ch.Assert(res == 0);
min = 0;
}
//If parsing as a ulong fails, we increment the counter for the non-key values.
else
{
var term = default(DvText);
getTerm(ref term);
if (countNonKeys < 5)
{
ch.Warning("Term '{0}' in mapping file is mapped to non key value '{1}'", term, txt);
}
countNonKeys++;
}
}
if (countNonKeys > 0)
{
ch.Warning("Found {0} non key values in the file '{1}'", countNonKeys, filename);
}
if (min > max)
{
min = 0;
max = uint.MaxValue - 1;
ch.Warning("did not find any valid key values in the file '{0}'", filename);
}
else
{
ch.Info("Found key values in the range {0} to {1} in the file '{2}'", min, max, filename);
}
ch.Done();
}
}
}
catch (Exception e)
{
throw host.Except(e, "Failed to parse the lookup file '{0}' in TermLookupTransform", filename);
}
TextLoader.Column valueColumn = new TextLoader.Column("Value", DataKind.U4, 1);
if (max - min < (ulong)int.MaxValue)
{
valueColumn.KeyRange = new KeyRange(min, max);
}
else if (max - min < (ulong)uint.MaxValue)
{
valueColumn.KeyRange = new KeyRange(min);
}
else
{
valueColumn.Type = DataKind.U8;
valueColumn.KeyRange = new KeyRange(min);
}
return(ComponentFactoryUtils.CreateFromFunction <IMultiStreamSource, IDataLoader>(
(env, files) => new TextLoader(
env,
new TextLoader.Arguments()
{
Column = new[]
{
new TextLoader.Column("Term", DataKind.TX, 0),
valueColumn
}
},
files)));
}