Question

我打开图像并将其转换为RGBA值数组。这是我的代码：

img = Image.open('17112013.png')
imgarray = array(img)
l = imgarray[:,1,1]
m = imgarray[1,:,1]
n = imgarray[1,1,:]
blueCount = 0
redCount = 0
flag = 0

for i in range(0,len(l)):
    for j in range(0,len(m)):
        if (imgarray[i,j] == [255,255,255,255]):
            pass
        if (imgarray[i,j] == [0,0,0,255] and flag == 0):
            pass
        if (imgarray[i,j] == [255,0,0,255] and flag == 0):
            pass
        if (imgarray[i,j] == [0,0,255,255]):
            flag = 1
            blueCount = blueCount + 1
        if (imgarray[i,j] == [255,0,0,255] and flag == 1):
            redCount = redCount + 1
        if (imgarray[i,j] == [0,0,0,255] and flag == 1):
            flag = 0
        if (imgarray[i,j] == [255,255,255,255] and flag == 1):
            flag = 0

如果我这样运行，我收到以下内容：

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

我知道我需要将这些用于＆＃39;如果＆＃39;包含numpy数组的语句;但是，我不确定实现它的正确语法。可能只是愚蠢，但任何帮助都会受到赞赏。

Answer 1

您可能需要以下内容：

if np.all(imgarray[i,j] == [255,255,255,255]):

如果imgarray的特定切片确实是[255,255,255,255]，则相等比较将返回array([ True, True, True, True], dtype=bool)。正如您所发现的那样，您不能指望if直接知道如何处理此布尔数组，但如果数组{中的所有值，则函数numpy.all(x)将返回True {1}}等同于x和True。

Answer 2

正如错误所说，当使用带有逻辑值数组的if时，不清楚你想要什么。我假设如果当前imgarray[i,j]的每个部分都等于比较数组，那么你只想要真。您最好使用过多的括号和逻辑&运算符来明确您想要的内容。运行，

import Image
import numpy as np

img = Image.open('17112013.png')
imgarray = np.array(img)
l = imgarray[:,1,1]
m = imgarray[1,:,1]
n = imgarray[1,1,:]
blueCount = 0
redCount = 0
flag = 0

for i in range(0,len(l)):
    for j in range(0,len(m)):
        if (np.all(imgarray[i,j] == [255,255,255,255])):
            pass
        if (np.all(imgarray[i,j] == [0,0,0,255]) & flag == 0):
            pass
        if (np.all(imgarray[i,j] == [255,0,0,255]) & flag == 0):
            pass
        if (np.all(imgarray[i,j] == [0,0,255,255])):
            flag = 1
            blueCount = blueCount + 1
        if (np.all(imgarray[i,j] == [255,0,0,255]) & flag == 1):
            redCount = redCount + 1
        if (np.all(imgarray[i,j] == [0,0,0,255]) & flag == 1):
            flag = 0
        if (np.all(imgarray[i,j] == [255,255,255,255]) & flag == 1):
            flag = 0

不确定你是否需要它？

Python - if语句涉及numpy数组

2 个答案: