Worked it out with some help.
You have to create a .Net DataSet and DataTable, add rows in memory, process the table and create a tab separated string from the data, then use a Stream to create a Spotfire TextDataSource...then you can create a data table in Spotfire using the in memory text data source (rather than a physical text file).
There is other stuff in this code related to the problem I was trying to solve, but it may be useful to other people.
import clr
clr.AddReference('System.Data')
import System
from System.Data import DataSet, DataTable, XmlReadMode
from Spotfire.Dxp.Data import DataType, DataTableSaveSettings
from System.IO import StringReader, StreamReader, StreamWriter, MemoryStream, SeekOrigin
from System.Threading import Thread
from Spotfire.Dxp.Data import IndexSet
from Spotfire.Dxp.Data import RowSelection
from Spotfire.Dxp.Data import DataValueCursor
from Spotfire.Dxp.Data import DataSelection
from Spotfire.Dxp.Data import DataPropertyClass
from Spotfire.Dxp.Data import Import
from System import DateTime
from System import DateTime, TimeSpan, DayOfWeek
from datetime import date
from System.Net import HttpWebRequest
import time
from Spotfire.Dxp.Data.Import import TextFileDataSource, TextDataReaderSettings
rowCount = Document.Data.Tables['Registrations'].RowCount
rowsToInclude = IndexSet(rowCount,True)
myList = []
#Get a cursor to the two columns we want to use. cursor1 is for the key column and cursor2 is for the column selected by the user input
registration = DataValueCursor.CreateFormatted(Document.Data.Tables['Registrations'].Columns["Registration ID"])
date1 = DataValueCursor.Create[DateTime](Document.Data.Tables['Registrations'].Columns["Date 1"])
date2 = DataValueCursor.Create[DateTime](Document.Data.Tables['Registrations'].Columns["Date 2"])
date3 = DataValueCursor.Create[DateTime](Document.Data.Tables['Registrations'].Columns["Date 3"])
date4 = DataValueCursor.Create[DateTime](Document.Data.Tables['Registrations'].Columns["Date 4"])
date5 = DataValueCursor.Create[DateTime](Document.Data.Tables['Registrations'].Columns["Date 5"])
#get users logon name not prid
#print Thread.CurrentPrincipal.Identity.Name
dataSet = DataSet()
dataTable = DataTable("pattern")
dataTable.Columns.Add("Registration ID", System.String)
dataTable.Columns.Add("Date 1", System.DateTime)
dataTable.Columns.Add("Date 2", System.DateTime)
dataTable.Columns.Add("Date 3", System.DateTime)
dataTable.Columns.Add("Date 4", System.DateTime)
dataTable.Columns.Add("Date 5", System.DateTime)
dataTable.Columns.Add("Sequence", System.String)
dataSet.Tables.Add(dataTable)
for row in Document.Data.Tables['Registrations'].GetRows(rowsToInclude,registration, date1,date2,date3, date4, date5):
dates=dict()
reg = registration.CurrentValue
value1 = date1.CurrentValue
value2 = date2.CurrentValue
value3 = date3.CurrentValue
value4 = date4.CurrentValue
value5 = date5.CurrentValue
dates['date1'] = value1
dates['date2'] = value2
dates['date3'] = value3
dates['date4'] = value4
dates['date5'] = value5
sortedDates = sorted(dates.values())
#print sorted(dates.values())
pattern = ""
for key, value in sorted(dates.iteritems(), key=lambda (k,v): (v,k)):
if str(value) <> '01/01/0001 00:00:00':
print 'Found a zero date'
if key == 'date1':
pattern = pattern + 'd1'
print 'Found a date 1'
if key == 'date2':
pattern = pattern + 'd2'
print 'Found a date 2'
if key == 'date3':
pattern = pattern + 'd3'
print 'Found a date 3'
if key == 'date4':
pattern = pattern + 'd4'
print 'Found a date 4'
if key == 'date5':
pattern = pattern + 'd5'
print 'Found a date 5'
dt = dataTable.NewRow()
dt["Registration ID"] = reg
dt["Date 1"] = value1
dt["Date 2"] = value2
dt["Date 3"] = value3
dt["Date 4"] = value4
dt["Date 5"] = value5
dt["Sequence"] = pattern
dataTable.Rows.Add(dt)
textData = "Registration ID\tDate 1\tDate 2\tDate 3\tDate 4\tDate 5\tSequence\r\n"
for row in dataTable.Rows:
textData += row["Registration ID"] + "\t" + str(row["Date 1"]) + "\t" + str(row["Date 2"]) + "\t" + str(row["Date 3"]) + "\t" + str(row["Date 4"]) + "\t" + str(row["Date 5"]) + "\t" + row["Sequence"] + "\r\n"
print textData
stream = MemoryStream()
writer = StreamWriter(stream)
writer.Write(textData)
writer.Flush()
stream.Seek(0, SeekOrigin.Begin)
readerSettings = TextDataReaderSettings()
readerSettings.Separator = "\t"
readerSettings.AddColumnNameRow(0)
readerSettings.SetDataType(0, DataType.String)
readerSettings.SetDataType(1, DataType.Date)
readerSettings.SetDataType(2, DataType.Date)
readerSettings.SetDataType(3, DataType.Date)
readerSettings.SetDataType(4, DataType.Date)
readerSettings.SetDataType(5, DataType.String)
dSource = TextFileDataSource(stream, readerSettings)
if Document.Data.Tables.Contains("Sequence"):
Document.Data.Tables["Sequence"].ReplaceData(dSource)
else:
newTable = Document.Data.Tables.Add("Sequence", dSource)
tableSettings = DataTableSaveSettings (newTable, False, False)
Document.Data.SaveSettings.DataTableSettings.Add(tableSettings)