Matplotlib imshow/matshow在地圖上顯示值

Question

我想在Matplotlib中使用imshow或matshow創建一個10x10網格。下面的函數將numpy數組作爲輸入，並繪製網格圖。但是，我想從陣列中的值也顯示在網格定義的單元格內。到目前爲止，我找不到一個正確的方法來做到這一點。我可以使用plt.text將東西放在網格上，但這需要每個單元的座標，完全不方便。有沒有更好的方式去做我想要完成的事情？

謝謝！

注意：下面的代碼沒有從數組中取值，我只是在玩plt.text。

import numpy as np 
import matplotlib.pyplot as plt 
from matplotlib import colors 

board = np.zeros((10, 10)) 

def visBoard(board): 
    cmap = colors.ListedColormap(['white', 'red']) 
    bounds=[0,0.5,1] 
    norm = colors.BoundaryNorm(bounds, cmap.N) 
    plt.figure(figsize=(4,4)) 
    plt.matshow(board, cmap=cmap, norm=norm, interpolation='none', vmin=0, vmax=1) 
    plt.xticks(np.arange(0.5,10.5), []) 
    plt.yticks(np.arange(0.5,10.5), []) 
    plt.text(-0.1, 0.2, 'x') 
    plt.text(0.9, 0.2, 'o') 
    plt.text(1.9, 0.2, 'x') 
    plt.grid() 

    visBoard(board) 

輸出：

Answer 1

你可以這樣做：

import numpy as np 
import matplotlib.pyplot as plt 

fig, ax = plt.subplots() 

min_val, max_val = 0, 10 
ind_array = np.arange(min_val + 0.5, max_val + 0.5, 1.0) 
x, y = np.meshgrid(ind_array, ind_array) 

for i, (x_val, y_val) in enumerate(zip(x.flatten(), y.flatten())): 
    c = 'x' if i%2 else 'o' 
    ax.text(x_val, y_val, c, va='center', ha='center') 
#alternatively, you could do something like 
#for x_val, y_val in zip(x.flatten(), y.flatten()): 
# c = 'x' if (x_val + y_val)%2 else 'o' 

ax.set_xlim(min_val, max_val) 
ax.set_ylim(min_val, max_val) 
ax.set_xticks(np.arange(max_val)) 
ax.set_yticks(np.arange(max_val)) 
ax.grid() 

---

編輯：

以下是帶有imshow背景的更新示例。

import numpy as np 
import matplotlib.pyplot as plt 

fig, ax = plt.subplots() 

min_val, max_val, diff = 0., 10., 1. 

#imshow portion 
N_points = (max_val - min_val)/diff 
imshow_data = np.random.rand(N_points, N_points) 
ax.imshow(imshow_data, interpolation='nearest') 

#text portion 
ind_array = np.arange(min_val, max_val, diff) 
x, y = np.meshgrid(ind_array, ind_array) 

for x_val, y_val in zip(x.flatten(), y.flatten()): 
    c = 'x' if (x_val + y_val)%2 else 'o' 
    ax.text(x_val, y_val, c, va='center', ha='center') 

#set tick marks for grid 
ax.set_xticks(np.arange(min_val-diff/2, max_val-diff/2)) 
ax.set_yticks(np.arange(min_val-diff/2, max_val-diff/2)) 
ax.set_xticklabels([]) 
ax.set_yticklabels([]) 
ax.set_xlim(min_val-diff/2, max_val-diff/2) 
ax.set_ylim(min_val-diff/2, max_val-diff/2) 
ax.grid() 
plt.show() 

Answer 2

爲了您的圖形，你應該應該嘗試與pyplot.table：

import matplotlib.pyplot as plt 
import numpy as np 

board = np.zeros((10, 10)) 
board[0,0] = 1 
board[0,1] = -1 
board[0,2] = 1 
def visBoard(board): 
    data = np.empty(board.shape,dtype=np.str) 
    data[:,:] = ' ' 
    data[board==1.0] = 'X' 
    data[board==-1.0] = 'O' 
    plt.axis('off') 
    size = np.ones(board.shape[0])/board.shape[0] 
    plt.table(cellText=data,loc='center',colWidths=size,cellLoc='center',bbox=[0,0,1,1]) 
    plt.show() 

visBoard(board) 

Answer 3

上@wflynny的代碼一些闡述使它成爲可以接收任意矩陣不管是什麼尺寸的功能並繪製其價值。

import numpy as np 
import matplotlib.pyplot as plt 

cols = np.random.randint(low=1,high=30) 
rows = np.random.randint(low=1,high=30) 
X = np.random.rand(rows,cols) 

def plotMat(X): 
    fig, ax = plt.subplots() 
    #imshow portion 
    ax.imshow(X, interpolation='nearest') 
    #text portion 
    diff = 1. 
    min_val = 0. 
    rows = X.shape[0] 
    cols = X.shape[1] 
    col_array = np.arange(min_val, cols, diff) 
    row_array = np.arange(min_val, rows, diff) 
    x, y = np.meshgrid(col_array, row_array) 
    for col_val, row_val in zip(x.flatten(), y.flatten()): 
     c = '+' if X[row_val.astype(int),col_val.astype(int)] < 0.5 else '-' 
     ax.text(col_val, row_val, c, va='center', ha='center') 
    #set tick marks for grid 
    ax.set_xticks(np.arange(min_val-diff/2, cols-diff/2)) 
    ax.set_yticks(np.arange(min_val-diff/2, rows-diff/2)) 
    ax.set_xticklabels([]) 
    ax.set_yticklabels([]) 
    ax.set_xlim(min_val-diff/2, cols-diff/2) 
    ax.set_ylim(min_val-diff/2, rows-diff/2) 
    ax.grid() 
    plt.show() 

plotMat(X)