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
  
  [![enter image description here](https://i.sstatic.net/mvzP2.png)](https://i.sstatic.net/mvzP2.png)
  
  ---
  
  e6\_board.png
  
  [![enter image description here](https://i.sstatic.net/Zt2ER.png)](https://i.sstatic.net/Zt2ER.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
  
  [![enter image description here](https://i.sstatic.net/dKoYA.png)](https://i.sstatic.net/dKoYA.png)
  
  
  ---
  
  