columnTypes property
For heterogeneous structures, get type information per column/dimension
Returns null for homogeneous structures or structures without named columns. For DataFrame, returns a map of column names to their inferred types.
Example:
var df = DataFrame({'a': [1, 2], 'b': ['x', 'y']});
print(df.columnTypes); // {'a': int, 'b': String}
var array = NDArray([1, 2, 3]);
print(array.columnTypes); // null
Implementation
Map<String, Type>? get columnTypes => null;