class_docstr: A scalable graph data structure. The SGraph data structure allows arbitrary
  dictionary attributes on vertices and edges, provides flexible vertex and
  edge query functions, and seamless transformation to and from
  :class:`~turicreate.SFrame`.
  
  There are several ways to create an SGraph. The simplest way is to make an
  empty SGraph then add vertices and edges with the :py:func:`add_vertices`
  and :py:func:`add_edges` methods. SGraphs can also be created from vertex
  and edge lists stored in :class:`~turicreate.SFrames`. Columns of these
  SFrames not used as vertex IDs are assumed to be vertex or edge attributes.
  
  Please see the `User Guide
  <https://apple.github.io/turicreate/docs/userguide/sgraph/sgraph.html>`_
  for a more detailed introduction to creating and working with SGraphs.
  
  Parameters
  ----------
  vertices : SFrame, optional
      Vertex data. Must include an ID column with the name specified by
      the `vid_field` parameter. Additional columns are treated as vertex
      attributes.
  
  edges : SFrame, optional
      Edge data. Must include source and destination ID columns as specified
      by `src_field` and `dst_field` parameters. Additional columns are treated
      as edge attributes.
  
  vid_field : str, optional
      The name of vertex ID column in the `vertices` SFrame.
  
  src_field : str, optional
      The name of source ID column in the `edges` SFrame.
  
  dst_field : str, optional
      The name of destination ID column in the `edges` SFrame.
  
  See Also
  --------
  SFrame
  
  Notes
  -----
  - SGraphs are *structurally immutable*. In the example below, the
    :func:`~add_vertices` and :func:`~add_edges` commands both return a new
    graph; the old graph gets garbage collected.
  
  Examples
  --------
  >>> from turicreate import SGraph, Vertex, Edge
  >>> g = SGraph()
  >>> verts = [Vertex(0, attr={'breed': 'labrador'}),
               Vertex(1, attr={'breed': 'labrador'}),
               Vertex(2, attr={'breed': 'vizsla'})]
  >>> g = g.add_vertices(verts)
  >>> g = g.add_edges(Edge(1, 2))
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docstr: Return a new SGraph with only the selected fields. Other fields are
  discarded, while fields that do not exist in the SGraph are ignored.
  
  Parameters
  ----------
  fields : string | list [string]
      A single field name or a list of field names to select.
  
  Returns
  -------
  out : SGraph
      A new graph whose vertex and edge data are projected to the selected
      fields.
  
  See Also
  --------
  get_fields, get_vertex_fields, get_edge_fields
  
  Examples
  --------
  >>> from turicreate import SGraph, Vertex
  >>> verts = [Vertex(0, attr={'breed': 'labrador', 'age': 5}),
               Vertex(1, attr={'breed': 'labrador', 'age': 3}),
               Vertex(2, attr={'breed': 'vizsla', 'age': 8})]
  >>> g = SGraph()
  >>> g = g.add_vertices(verts)
  >>> g2 = g.select_fields(fields=['breed'])
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code: def select_fields(self, fields):
      """
      Return a new SGraph with only the selected fields. Other fields are
      discarded, while fields that do not exist in the SGraph are ignored.
  
      Parameters
      ----------
      fields : string | list [string]
          A single field name or a list of field names to select.
  
      Returns
      -------
      out : SGraph
          A new graph whose vertex and edge data are projected to the selected
          fields.
  
      See Also
      --------
      get_fields, get_vertex_fields, get_edge_fields
  
      Examples
      --------
      >>> from turicreate import SGraph, Vertex
      >>> verts = [Vertex(0, attr={'breed': 'labrador', 'age': 5}),
                   Vertex(1, attr={'breed': 'labrador', 'age': 3}),
                   Vertex(2, attr={'breed': 'vizsla', 'age': 8})]
      >>> g = SGraph()
      >>> g = g.add_vertices(verts)
      >>> g2 = g.select_fields(fields=['breed'])
      """
  
      if type(fields) is str:
          fields = [fields]
      if not isinstance(fields, list) or not all(
          type(x) is str for x in fields
      ):
          raise TypeError('"fields" must be a str or list[str]')
  
      vfields = self.__proxy__.get_vertex_fields()
      efields = self.__proxy__.get_edge_fields()
      selected_vfields = []
      selected_efields = []
      for f in fields:
          found = False
          if f in vfields:
              selected_vfields.append(f)
              found = True
          if f in efields:
              selected_efields.append(f)
              found = True
          if not found:
              raise ValueError("Field '%s' not in graph" % f)
  
      with cython_context():
          proxy = self.__proxy__
          proxy = proxy.select_vertex_fields(selected_vfields)
          proxy = proxy.select_edge_fields(selected_efields)
          return SGraph(_proxy=proxy)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from .._connect import main
  from .sframe import SFrame
  from .sarray import SArray
  from .gframe import GFrame, VERTEX_GFRAME, EDGE_GFRAME
  from .._cython.cy_graph import UnityGraphProxy
  from .._cython.context import debug_trace
  from ..util import _is_non_string_iterable, _make_internal_url
  from .._deps import pandas
  from .._deps import HAS_PANDAS
  import inspect
  import copy
  import sys
label_desc: Use image node_id 17 for calling the SGraph obj's underlying member method code with example usage: obj.select_fields(fields) and returns: SGraph