B4J Code Snippet [PyBridge] [LOA] ListOfArrays - DataFrames

DataFrame is a core type in many Python libraries. The following subs make it simple to convert LOAs to DataFrames and vice versa.

'Adds a converter that converts dataframes to a list of arrays (not LOA yet) when a dataframe is fetched.
Private Sub AddDataFrameConverter
    Dim Pandas As PyWrapper = Py.ImportModule("pandas")
    Dim converters As PyWrapper = Py.Bridge.GetField("comm").GetField("serializator").GetField("converters")
    converters.Set(Pandas.GetField("DataFrame"), Py.Lambda("df: [tuple(df.columns)] + list(df.itertuples(index=False, name=None))"))
End Sub

'Converts a LOA to DataFrame.
Public Sub LOAToDataFrame (LOA As ListOfArrays) As PyWrapper
    Dim Code As String = $"
def LOAToDataFrame (LOA):
    df = pandas.DataFrame(LOA[1:], columns=LOA[0])
    return df
"$
    Return Py.RunCode("LOAToDataFrame", Array(LOA.mInternalArray), Code)
End Sub

Call AddDataFrameConverter once when the program starts.

To fetch a DataFrame:

Wait For (df.Fetch) Complete (df As PyWrapper)
Dim table2 As ListOfArrays = LOAUtils.WrapWithHeader(df.Value)

To convert a LOA to DataFrame:

Dim df As PyWrapper = LOAToDataFrame(table)
df.Print

Example:

AddDataFrameConverter

Dim table As ListOfArrays = LOAUtils.CreateEmpty((Array("Id", "Animal type", "Name", "Age", "Weight")))
table.AddRow(Array(1, "Rabbit", "Coco", 3, 2.4))
table.AddRow(Array(2, "Cat", "Luna", 2, 4.1))
table.AddRow(Array(3, "Dog", "Rocky", 8, 25.6))
table.AddRow(Array(4, "Parrot", "Kiwi", 7, 0.9))
table.AddRow(Array(5, "Hamster", "Nibbles", 1, 0.2))
table.AddRow(Array(6, "Goat", "Daisy", 4, 35.0))
table.AddRow(Array(7, "Cat", "Shadow", 9, 5.2))

Dim df As PyWrapper = LOAToDataFrame(table)
df.Print
Wait For (df.Fetch) Complete (df As PyWrapper)
Dim table2 As ListOfArrays = LOAUtils.WrapWithHeader(df.Value)
Log(table2.ToString(0))