Answers.Body: <p>This python script will show how many white/black attackers on every square.</p>
  <p>It will also generate an image in <code>png</code> format where the attacked square is marked with <code>X</code> and the attacker locations are colored green.</p>
  <p>Edit: Added code to generate an attack heatmap.
  Edit: Update attack heatmap board labels.</p>
  <h2>Code</h2>
  <pre><code>&quot;&quot;&quot;
  pip install chess
  pip install cairosvg
  &quot;&quot;&quot;
  
  import chess
  import chess.svg
  from cairosvg import svg2png
  
  
  def main():
      fen = 'rn1r3k/pp2qpp1/1bb1p3/6p1/2BP4/P4N2/1PQ1RPPP/4R1K1 w - - 0 19'
  
      board = chess.Board(fen)
      print(board)
      print()
  
      for square in range(64):
          sq_name = chess.square_name(square)
          w_attackers = board.attackers(chess.WHITE, square)
          b_attackers = board.attackers(chess.BLACK, square)
  
          svg = chess.svg.board(
              board,
              fill=dict.fromkeys((w_attackers | b_attackers), &quot;#00FF00&quot;),
              squares=(chess.SquareSet([square])),
              size=350,
          )
  
          png_fn = f'{sq_name}_board.png'
          svg2png(bytestring=svg, write_to=png_fn)
  
          print(f'sq: {sq_name}, wattackers: {len(list(w_attackers))}, battackers: {len(list(b_attackers))}')
  
  
  if __name__ == '__main__':
      main()
  </code></pre>
  <h2>Sample Image Output</h2>
  <p>a4_board.png</p>
  <p><a href="https://i.sstatic.net/mvzP2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/mvzP2.png" alt="enter image description here" /></a></p>
  <hr />
  <p>e6_board.png</p>
  <p><a href="https://i.sstatic.net/Zt2ER.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Zt2ER.png" alt="enter image description here" /></a></p>
  <hr />
  <h2>Sample Text Output</h2>
  <pre><code>r n . r . . . k
  p p . . q p p .
  . b b . p . . .
  . . . . . . p .
  . . B P . . . .
  P . . . . N . .
  . P Q . R P P P
  . . . . R . K .
  
  sq: a1, wattackers: 1, battackers: 0
  sq: b1, wattackers: 2, battackers: 0
  sq: c1, wattackers: 2, battackers: 0
  sq: d1, wattackers: 2, battackers: 0
  sq: e1, wattackers: 2, battackers: 0
  sq: f1, wattackers: 2, battackers: 0
  sq: g1, wattackers: 2, battackers: 0
  sq: h1, wattackers: 1, battackers: 0
  sq: a2, wattackers: 1, battackers: 0
  sq: b2, wattackers: 1, battackers: 0
  sq: c2, wattackers: 1, battackers: 0
  sq: d2, wattackers: 3, battackers: 0
  sq: e2, wattackers: 3, battackers: 0
  sq: f2, wattackers: 2, battackers: 0
  sq: g2, wattackers: 1, battackers: 0
  sq: h2, wattackers: 2, battackers: 0
  sq: a3, wattackers: 1, battackers: 1
  sq: b3, wattackers: 2, battackers: 0
  sq: c3, wattackers: 2, battackers: 0
  sq: d3, wattackers: 2, battackers: 0
  sq: e3, wattackers: 2, battackers: 0
  sq: f3, wattackers: 1, battackers: 1
  sq: g3, wattackers: 2, battackers: 0
  sq: h3, wattackers: 1, battackers: 0
  sq: a4, wattackers: 1, battackers: 1
  sq: b4, wattackers: 1, battackers: 1
  sq: c4, wattackers: 1, battackers: 0
  sq: d4, wattackers: 1, battackers: 2
  sq: e4, wattackers: 2, battackers: 1
  sq: f4, wattackers: 0, battackers: 1
  sq: g4, wattackers: 0, battackers: 0
  sq: h4, wattackers: 1, battackers: 1
  sq: a5, wattackers: 0, battackers: 1
  sq: b5, wattackers: 1, battackers: 1
  sq: c5, wattackers: 1, battackers: 2
  sq: d5, wattackers: 1, battackers: 3
  sq: e5, wattackers: 3, battackers: 0
  sq: f5, wattackers: 1, battackers: 1
  sq: g5, wattackers: 1, battackers: 1
  sq: h5, wattackers: 0, battackers: 0
  sq: a6, wattackers: 1, battackers: 2
  sq: b6, wattackers: 0, battackers: 1
  sq: c6, wattackers: 0, battackers: 2
  sq: d6, wattackers: 0, battackers: 2
  sq: e6, wattackers: 2, battackers: 2
  sq: f6, wattackers: 0, battackers: 2
  sq: g6, wattackers: 1, battackers: 1
  sq: h6, wattackers: 0, battackers: 1
  sq: a7, wattackers: 0, battackers: 2
  sq: b7, wattackers: 0, battackers: 2
  sq: c7, wattackers: 0, battackers: 2
  sq: d7, wattackers: 0, battackers: 4
  sq: e7, wattackers: 0, battackers: 0
  sq: f7, wattackers: 0, battackers: 1
  sq: g7, wattackers: 0, battackers: 1
  sq: h7, wattackers: 1, battackers: 1
  sq: a8, wattackers: 0, battackers: 0
  sq: b8, wattackers: 0, battackers: 2
  sq: c8, wattackers: 0, battackers: 1
  sq: d8, wattackers: 0, battackers: 2
  sq: e8, wattackers: 0, battackers: 3
  sq: f8, wattackers: 0, battackers: 2
  sq: g8, wattackers: 0, battackers: 2
  sq: h8, wattackers: 0, battackers: 1
  </code></pre>
  <p>You have to change the FEN in the code for other positions.</p>
  <h2>Updated code to generate an attack heatmap</h2>
  <p>The map is saved in html file.</p>
  <pre><code>&quot;&quot;&quot;
  pip install chess
  pip install cairosvg
  pip install numpy
  pip install plotly
  &quot;&quot;&quot;
  
  import chess
  import chess.svg
  from cairosvg import svg2png
  import plotly.express as px
  import numpy
  
  
  def main():
      fen = 'rn1r3k/pp2qpp1/1bb1p3/6p1/2BP4/P4N2/1PQ1RPPP/4R1K1 w - - 0 19'
  
      board = chess.Board(fen)
      print(board)
      print()
  
      att = {i: 0 for i in range(64)}
  
      for square in range(64):
          sq_name = chess.square_name(square)
          w_attackers = board.attackers(chess.WHITE, square)
          b_attackers = board.attackers(chess.BLACK, square)
  
          att[square] += len(w_attackers) + len(b_attackers)
  
          svg = chess.svg.board(
              board,
              fill=dict.fromkeys((w_attackers | b_attackers), &quot;#00FF00&quot;),
              squares=(chess.SquareSet([square])),
              size=350,
          )
  
          png_fn = f'{sq_name}_board.png'
          svg2png(bytestring=svg, write_to=png_fn)
  
          print(f'sq: {sq_name}, wattackers: {len(list(w_attackers))}, battackers: {len(list(b_attackers))}')
  
      # Create a heatmap using plotly.
      att_list = []
      for k, v in att.items():
          att_list.append(v)
  
      np_arr = numpy.array(att_list)
      np_arr_8_by_8 = np_arr.reshape(8, 8)
      np_arr_8_by_8_flip = numpy.flip(np_arr_8_by_8, 0)
  
      fig = px.imshow(np_arr_8_by_8_flip, text_auto=True,
                  labels=dict(color='numattacks'),
                  x=['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'],
                  y=['8', '7', '6', '5', '4', '3', '2', '1'])
      fig.write_html('attack_heatmap.html')
      # fig.show()
  
  
  if __name__ == '__main__':
      main()
  </code></pre>
  <p>Output</p>
  <p><a href="https://i.sstatic.net/dKoYA.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/dKoYA.png" alt="enter image description here" /></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-04-05T14:28:51.507Z
Answers.LastActivityDate: 2023-04-06T00:02:00.120Z
Answers.LastEditDate: 2023-04-06T00:02:00.120Z
Answers.UserDisplayName: ferdy
Body: <p>Are there any software programs or tools available that can display the number of pieces attacking each square?</p>
  
Tags: <software><chessboards><visualization>
Title: Visualizing the number of pieces attacking each square
ThreadText: # Visualizing the number of pieces attacking each square
  
  (Asked by: username_0 on 2023-04-03)
  
  Are there any software programs or tools available that can display the number of pieces attacking each square?
  
  **Tags:** software, chessboards, visualization
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2023-04-05. Score: 3
  
  This python script will show how many white/black attackers on every square.
  It will also generate an image in png format where the attacked square is marked with X and the attacker locations are colored green.
  Edit: Added code to generate an attack heatmap.
  Edit: Update attack heatmap board labels.
  Code
  """
  pip install chess
  pip install cairosvg
  """
  
  import chess
  import chess.svg
  from cairosvg import svg2png
  
  
  def main():
      fen = 'rn1r3k/pp2qpp1/1bb1p3/6p1/2BP4/P4N2/1PQ1RPPP/4R1K1 w - - 0 19'
  
      board = chess.Board(fen)
      print(board)
      print()
  
      for square in range(64):
          sq_name = chess.square_name(square)
          w_attackers = board.attackers(chess.WHITE, square)
          b_attackers = board.attackers(chess.BLACK, square)
  
          svg = chess.svg.board(
              board,
              fill=dict.fromkeys((w_attackers | b_attackers), "#00FF00"),
              squares=(chess.SquareSet([square])),
              size=350,
          )
  
          png_fn = f'{sq_name}_board.png'
          svg2png(bytestring=svg, write_to=png_fn)
  
          print(f'sq: {sq_name}, wattackers: {len(list(w_attackers))}, battackers: {len(list(b_attackers))}')
  
  
  if __name__ == '__main__':
      main()
  
  Sample Image Output
  a4_board.png
  
  
  e6_board.png
  
  
  Sample Text Output
  r n . r . . . k
  p p . . q p p .
  . b b . p . . .
  . . . . . . p .
  . . B P . . . .
  P . . . . N . .
  . P Q . R P P P
  . . . . R . K .
  
  sq: a1, wattackers: 1, battackers: 0
  sq: b1, wattackers: 2, battackers: 0
  sq: c1, wattackers: 2, battackers: 0
  sq: d1, wattackers: 2, battackers: 0
  sq: e1, wattackers: 2, battackers: 0
  sq: f1, wattackers: 2, battackers: 0
  sq: g1, wattackers: 2, battackers: 0
  sq: h1, wattackers: 1, battackers: 0
  sq: a2, wattackers: 1, battackers: 0
  sq: b2, wattackers: 1, battackers: 0
  sq: c2, wattackers: 1, battackers: 0
  sq: d2, wattackers: 3, battackers: 0
  sq: e2, wattackers: 3, battackers: 0
  sq: f2, wattackers: 2, battackers: 0
  sq: g2, wattackers: 1, battackers: 0
  sq: h2, wattackers: 2, battackers: 0
  sq: a3, wattackers: 1, battackers: 1
  sq: b3, wattackers: 2, battackers: 0
  sq: c3, wattackers: 2, battackers: 0
  sq: d3, wattackers: 2, battackers: 0
  sq: e3, wattackers: 2, battackers: 0
  sq: f3, wattackers: 1, battackers: 1
  sq: g3, wattackers: 2, battackers: 0
  sq: h3, wattackers: 1, battackers: 0
  sq: a4, wattackers: 1, battackers: 1
  sq: b4, wattackers: 1, battackers: 1
  sq: c4, wattackers: 1, battackers: 0
  sq: d4, wattackers: 1, battackers: 2
  sq: e4, wattackers: 2, battackers: 1
  sq: f4, wattackers: 0, battackers: 1
  sq: g4, wattackers: 0, battackers: 0
  sq: h4, wattackers: 1, battackers: 1
  sq: a5, wattackers: 0, battackers: 1
  sq: b5, wattackers: 1, battackers: 1
  sq: c5, wattackers: 1, battackers: 2
  sq: d5, wattackers: 1, battackers: 3
  sq: e5, wattackers: 3, battackers: 0
  sq: f5, wattackers: 1, battackers: 1
  sq: g5, wattackers: 1, battackers: 1
  sq: h5, wattackers: 0, battackers: 0
  sq: a6, wattackers: 1, battackers: 2
  sq: b6, wattackers: 0, battackers: 1
  sq: c6, wattackers: 0, battackers: 2
  sq: d6, wattackers: 0, battackers: 2
  sq: e6, wattackers: 2, battackers: 2
  sq: f6, wattackers: 0, battackers: 2
  sq: g6, wattackers: 1, battackers: 1
  sq: h6, wattackers: 0, battackers: 1
  sq: a7, wattackers: 0, battackers: 2
  sq: b7, wattackers: 0, battackers: 2
  sq: c7, wattackers: 0, battackers: 2
  sq: d7, wattackers: 0, battackers: 4
  sq: e7, wattackers: 0, battackers: 0
  sq: f7, wattackers: 0, battackers: 1
  sq: g7, wattackers: 0, battackers: 1
  sq: h7, wattackers: 1, battackers: 1
  sq: a8, wattackers: 0, battackers: 0
  sq: b8, wattackers: 0, battackers: 2
  sq: c8, wattackers: 0, battackers: 1
  sq: d8, wattackers: 0, battackers: 2
  sq: e8, wattackers: 0, battackers: 3
  sq: f8, wattackers: 0, battackers: 2
  sq: g8, wattackers: 0, battackers: 2
  sq: h8, wattackers: 0, battackers: 1
  
  You have to change the FEN in the code for other positions.
  Updated code to generate an attack heatmap
  The map is saved in html file.
  """
  pip install chess
  pip install cairosvg
  pip install numpy
  pip install plotly
  """
  
  import chess
  import chess.svg
  from cairosvg import svg2png
  import plotly.express as px
  import numpy
  
  
  def main():
      fen = 'rn1r3k/pp2qpp1/1bb1p3/6p1/2BP4/P4N2/1PQ1RPPP/4R1K1 w - - 0 19'
  
      board = chess.Board(fen)
      print(board)
      print()
  
      att = {i: 0 for i in range(64)}
  
      for square in range(64):
          sq_name = chess.square_name(square)
          w_attackers = board.attackers(chess.WHITE, square)
          b_attackers = board.attackers(chess.BLACK, square)
  
          att[square] += len(w_attackers) + len(b_attackers)
  
          svg = chess.svg.board(
              board,
              fill=dict.fromkeys((w_attackers | b_attackers), "#00FF00"),
              squares=(chess.SquareSet([square])),
              size=350,
          )
  
          png_fn = f'{sq_name}_board.png'
          svg2png(bytestring=svg, write_to=png_fn)
  
          print(f'sq: {sq_name}, wattackers: {len(list(w_attackers))}, battackers: {len(list(b_attackers))}')
  
      # Create a heatmap using plotly.
      att_list = []
      for k, v in att.items():
          att_list.append(v)
  
      np_arr = numpy.array(att_list)
      np_arr_8_by_8 = np_arr.reshape(8, 8)
      np_arr_8_by_8_flip = numpy.flip(np_arr_8_by_8, 0)
  
      fig = px.imshow(np_arr_8_by_8_flip, text_auto=True,
                  labels=dict(color='numattacks'),
                  x=['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'],
                  y=['8', '7', '6', '5', '4', '3', '2', '1'])
      fig.write_html('attack_heatmap.html')
      # fig.show()
  
  
  if __name__ == '__main__':
      main()
  
  Output
  
  
  ---
  
  