prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  nilearn.plotting overrides the matplotlib backend, causing troubles on remote SSH development
  I am working on a remote settings, accessing a machine (drago/margaret for INRIA context) through a PyCharm Remote Interpreter.
  I have been struggling to display nilearn figures in the scientific view of PyCharm, leading to a painful process of saving the image => rsync figures dir => visualize figures once there are on personal laptop.
  
  I did a simple experiment drawing first a simple `plot(list(range(10)))` which is displayed and then a nilearn figure which does not show up (script at the end of the issue).
  
  I found out the reason for this, which is that in `nilearn.plotting.__init__`, the matplotlib backend is set to `agg` if not in `[inline, agg]`, but the backend used initially (which is working for me) is `module://backend_interagg`.
  
  Setting the backend to the initial value after importing `nilearn.datasets` fixes the problem.
  
  I don't know exactly how those matplotlib backends work, if the list of accepted backends in `nilearn.datasets.__init__` could be extended or if we could have a more robust list of valid matplotlib backend. Also, I feel that nilearn shouldn't override matplotlib backend silently? 
  
  <!--Please fill in the following information, to the best of your ability.-->
  Nilearn version: 0.7.1
  
  ### Expected behavior
  
  Nilearn does not override matplotlib backend silently.
  
  ### Actual behavior
  
  Nilearn sets backend to "agg" if not in ["inline", "agg"], causing trouble with remote SSH development.
  
  ### Steps and code to reproduce bug
  
  Run the following script through SSH remote interpreter
  
  ```python
  import matplotlib
  initial_backend = matplotlib.get_backend().lower()
  print(initial_backend)
  
  import matplotlib.pyplot as plt
  import numpy as np
  
  arr = np.zeros((100, 100))
  plt.figure()
  plt.plot(list(range(10)))
  plt.show()
  # >> The show is displayed in PyCharm
  
  from nilearn import datasets, plotting
  print(matplotlib.get_backend().lower())
  # >> Backend has switched to "agg"
  
  sample_brain_map = datasets.fetch_neurovault_motor_task().images[0]
  plotting.plot_stat_map(
      sample_brain_map,
      threshold=3,
      title="Before setting back the backend",
  )
  
  plt.show()
  # >> Does not show up
  
  matplotlib.use(initial_backend)
  plotting.plot_stat_map(
      sample_brain_map,
      threshold=3,
      title="After setting back the backend",
  )
  
  plt.show()
  # >> Shows up
  
  ```
  
  
  </issue>
  <code>
  [start of nilearn/plotting/__init__.py]
  1 """
  2 Plotting code for nilearn
  3 """
  4 # Original Authors: Chris Filo Gorgolewski, Gael Varoquaux
  5 import os
  6 import sys
  7 import importlib
  8 
  9 
  10 ###############################################################################
  11 # Make sure that we don't get DISPLAY problems when running without X on
  12 # unices
  13 def _set_mpl_backend():
  14     # We are doing local imports here to avoid polluting our namespace
  15     try:
  16         import matplotlib
  17     except ImportError:
  18         if importlib.util.find_spec("pytest") is not None:
  19             from .._utils.testing import skip_if_running_tests
  20             # No need to fail when running tests
  21             skip_if_running_tests('matplotlib not installed')
  22         raise
  23     else:
  24         from ..version import (_import_module_with_version_check,
  25                                OPTIONAL_MATPLOTLIB_MIN_VERSION)
  26         # When matplotlib was successfully imported we need to check
  27         # that the version is greater that the minimum required one
  28         _import_module_with_version_check('matplotlib',
  29                                           OPTIONAL_MATPLOTLIB_MIN_VERSION)
  30         current_backend = matplotlib.get_backend().lower()
  31 
  32         if 'inline' in current_backend or 'nbagg' in current_backend:
  33             return
  34         # Set the backend to a non-interactive one for unices without X
  35         # (see gh-2560)
  36         if (sys.platform not in ('darwin', 'win32') and
  37                 'DISPLAY' not in os.environ):
  38             matplotlib.use('Agg')
  39 
  40 
  41 _set_mpl_backend()
  42 
  43 ###############################################################################
  44 from . import cm
  45 from .img_plotting import (
  46     plot_img, plot_anat, plot_epi, plot_roi, plot_stat_map,
  47     plot_glass_brain, plot_connectome, plot_connectome_strength,
  48     plot_markers, plot_prob_atlas, plot_carpet, plot_img_comparison, show)
  49 from .find_cuts import find_xyz_cut_coords, find_cut_slices, \
  50     find_parcellation_cut_coords, find_probabilistic_atlas_cut_coords
  51 from .matrix_plotting import (plot_matrix, plot_contrast_matrix,
  52                               plot_design_matrix, plot_event)
  53 from .html_surface import view_surf, view_img_on_surf
  54 from .html_stat_map import view_img
  55 from .html_connectome import view_connectome, view_markers
  56 from .surf_plotting import (plot_surf, plot_surf_stat_map, plot_surf_roi,
  57                             plot_img_on_surf, plot_surf_contours)
  58 
  59 __all__ = ['cm', 'plot_img', 'plot_anat', 'plot_epi',
  60            'plot_roi', 'plot_stat_map', 'plot_glass_brain',
  61            'plot_markers', 'plot_connectome', 'plot_prob_atlas',
  62            'find_xyz_cut_coords', 'find_cut_slices',
  63            'plot_img_comparison',
  64            'show', 'plot_matrix',
  65            'plot_design_matrix', 'plot_contrast_matrix', 'plot_event',
  66            'view_surf', 'view_img_on_surf',
  67            'view_img', 'view_connectome', 'view_markers',
  68            'find_parcellation_cut_coords',
  69            'find_probabilistic_atlas_cut_coords',
  70            'plot_surf', 'plot_surf_stat_map', 'plot_surf_roi',
  71            'plot_img_on_surf', 'plot_connectome_strength', 'plot_carpet',
  72            'plot_surf_contours']
  73
  [end of nilearn/plotting/__init__.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/nilearn/plotting/__init__.py b/nilearn/plotting/__init__.py
  --- a/nilearn/plotting/__init__.py
  +++ b/nilearn/plotting/__init__.py
  @@ -2,9 +2,8 @@
   Plotting code for nilearn
   """
   # Original Authors: Chris Filo Gorgolewski, Gael Varoquaux
  -import os
  -import sys
   import importlib
  +import warnings
   
   
   ###############################################################################
  @@ -29,13 +28,17 @@
                                             OPTIONAL_MATPLOTLIB_MIN_VERSION)
           current_backend = matplotlib.get_backend().lower()
   
  -        if 'inline' in current_backend or 'nbagg' in current_backend:
  -            return
  -        # Set the backend to a non-interactive one for unices without X
  -        # (see gh-2560)
  -        if (sys.platform not in ('darwin', 'win32') and
  -                'DISPLAY' not in os.environ):
  -            matplotlib.use('Agg')
  +        try:
  +            # Making sure the current backend is usable by matplotlib
  +            matplotlib.use(current_backend)
  +        except Exception:
  +            # If not, switching to default agg backend
  +            matplotlib.use("Agg")
  +        new_backend = matplotlib.get_backend().lower()
  +
  +        if new_backend != current_backend:
  +            # Matplotlib backend has been changed, let's warn the user
  +            warnings.warn(f"Backend changed to {new_backend}...")
   
   
   _set_mpl_backend()
  
verification_info: {"golden_diff": "diff --git a/nilearn/plotting/__init__.py b/nilearn/plotting/__init__.py\n--- a/nilearn/plotting/__init__.py\n+++ b/nilearn/plotting/__init__.py\n@@ -2,9 +2,8 @@\n Plotting code for nilearn\n \"\"\"\n # Original Authors: Chris Filo Gorgolewski, Gael Varoquaux\n-import os\n-import sys\n import importlib\n+import warnings\n \n \n ###############################################################################\n@@ -29,13 +28,17 @@\n                                           OPTIONAL_MATPLOTLIB_MIN_VERSION)\n         current_backend = matplotlib.get_backend().lower()\n \n-        if 'inline' in current_backend or 'nbagg' in current_backend:\n-            return\n-        # Set the backend to a non-interactive one for unices without X\n-        # (see gh-2560)\n-        if (sys.platform not in ('darwin', 'win32') and\n-                'DISPLAY' not in os.environ):\n-            matplotlib.use('Agg')\n+        try:\n+            # Making sure the current backend is usable by matplotlib\n+            matplotlib.use(current_backend)\n+        except Exception:\n+            # If not, switching to default agg backend\n+            matplotlib.use(\"Agg\")\n+        new_backend = matplotlib.get_backend().lower()\n+\n+        if new_backend != current_backend:\n+            # Matplotlib backend has been changed, let's warn the user\n+            warnings.warn(f\"Backend changed to {new_backend}...\")\n \n \n _set_mpl_backend()\n", "issue": "nilearn.plotting overrides the matplotlib backend, causing troubles on remote SSH development\nI am working on a remote settings, accessing a machine (drago/margaret for INRIA context) through a PyCharm Remote Interpreter.\r\nI have been struggling to display nilearn figures in the scientific view of PyCharm, leading to a painful process of saving the image => rsync figures dir => visualize figures once there are on personal laptop.\r\n\r\nI did a simple experiment drawing first a simple `plot(list(range(10)))` which is displayed and then a nilearn figure which does not show up (script at the end of the issue).\r\n\r\nI found out the reason for this, which is that in `nilearn.plotting.__init__`, the matplotlib backend is set to `agg` if not in `[inline, agg]`, but the backend used initially (which is working for me) is `module://backend_interagg`.\r\n\r\nSetting the backend to the initial value after importing `nilearn.datasets` fixes the problem.\r\n\r\nI don't know exactly how those matplotlib backends work, if the list of accepted backends in `nilearn.datasets.__init__` could be extended or if we could have a more robust list of valid matplotlib backend. Also, I feel that nilearn shouldn't override matplotlib backend silently? \r\n\r\n<!--Please fill in the following information, to the best of your ability.-->\r\nNilearn version: 0.7.1\r\n\r\n### Expected behavior\r\n\r\nNilearn does not override matplotlib backend silently.\r\n\r\n### Actual behavior\r\n\r\nNilearn sets backend to \"agg\" if not in [\"inline\", \"agg\"], causing trouble with remote SSH development.\r\n\r\n### Steps and code to reproduce bug\r\n\r\nRun the following script through SSH remote interpreter\r\n\r\n```python\r\nimport matplotlib\r\ninitial_backend = matplotlib.get_backend().lower()\r\nprint(initial_backend)\r\n\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\narr = np.zeros((100, 100))\r\nplt.figure()\r\nplt.plot(list(range(10)))\r\nplt.show()\r\n# >> The show is displayed in PyCharm\r\n\r\nfrom nilearn import datasets, plotting\r\nprint(matplotlib.get_backend().lower())\r\n# >> Backend has switched to \"agg\"\r\n\r\nsample_brain_map = datasets.fetch_neurovault_motor_task().images[0]\r\nplotting.plot_stat_map(\r\n    sample_brain_map,\r\n    threshold=3,\r\n    title=\"Before setting back the backend\",\r\n)\r\n\r\nplt.show()\r\n# >> Does not show up\r\n\r\nmatplotlib.use(initial_backend)\r\nplotting.plot_stat_map(\r\n    sample_brain_map,\r\n    threshold=3,\r\n    title=\"After setting back the backend\",\r\n)\r\n\r\nplt.show()\r\n# >> Shows up\r\n\r\n```\r\n\n", "before_files": [{"content": "\"\"\"\nPlotting code for nilearn\n\"\"\"\n# Original Authors: Chris Filo Gorgolewski, Gael Varoquaux\nimport os\nimport sys\nimport importlib\n\n\n###############################################################################\n# Make sure that we don't get DISPLAY problems when running without X on\n# unices\ndef _set_mpl_backend():\n    # We are doing local imports here to avoid polluting our namespace\n    try:\n        import matplotlib\n    except ImportError:\n        if importlib.util.find_spec(\"pytest\") is not None:\n            from .._utils.testing import skip_if_running_tests\n            # No need to fail when running tests\n            skip_if_running_tests('matplotlib not installed')\n        raise\n    else:\n        from ..version import (_import_module_with_version_check,\n                               OPTIONAL_MATPLOTLIB_MIN_VERSION)\n        # When matplotlib was successfully imported we need to check\n        # that the version is greater that the minimum required one\n        _import_module_with_version_check('matplotlib',\n                                          OPTIONAL_MATPLOTLIB_MIN_VERSION)\n        current_backend = matplotlib.get_backend().lower()\n\n        if 'inline' in current_backend or 'nbagg' in current_backend:\n            return\n        # Set the backend to a non-interactive one for unices without X\n        # (see gh-2560)\n        if (sys.platform not in ('darwin', 'win32') and\n                'DISPLAY' not in os.environ):\n            matplotlib.use('Agg')\n\n\n_set_mpl_backend()\n\n###############################################################################\nfrom . import cm\nfrom .img_plotting import (\n    plot_img, plot_anat, plot_epi, plot_roi, plot_stat_map,\n    plot_glass_brain, plot_connectome, plot_connectome_strength,\n    plot_markers, plot_prob_atlas, plot_carpet, plot_img_comparison, show)\nfrom .find_cuts import find_xyz_cut_coords, find_cut_slices, \\\n    find_parcellation_cut_coords, find_probabilistic_atlas_cut_coords\nfrom .matrix_plotting import (plot_matrix, plot_contrast_matrix,\n                              plot_design_matrix, plot_event)\nfrom .html_surface import view_surf, view_img_on_surf\nfrom .html_stat_map import view_img\nfrom .html_connectome import view_connectome, view_markers\nfrom .surf_plotting import (plot_surf, plot_surf_stat_map, plot_surf_roi,\n                            plot_img_on_surf, plot_surf_contours)\n\n__all__ = ['cm', 'plot_img', 'plot_anat', 'plot_epi',\n           'plot_roi', 'plot_stat_map', 'plot_glass_brain',\n           'plot_markers', 'plot_connectome', 'plot_prob_atlas',\n           'find_xyz_cut_coords', 'find_cut_slices',\n           'plot_img_comparison',\n           'show', 'plot_matrix',\n           'plot_design_matrix', 'plot_contrast_matrix', 'plot_event',\n           'view_surf', 'view_img_on_surf',\n           'view_img', 'view_connectome', 'view_markers',\n           'find_parcellation_cut_coords',\n           'find_probabilistic_atlas_cut_coords',\n           'plot_surf', 'plot_surf_stat_map', 'plot_surf_roi',\n           'plot_img_on_surf', 'plot_connectome_strength', 'plot_carpet',\n           'plot_surf_contours']\n", "path": "nilearn/plotting/__init__.py"}]}