在Python中使用NumPy进行布尔数组索引时,如果遇到“ValueError: NumPy boolean array indexing assignment cannot assign 3 input values to the N output values where the mask is true”这样的错误,通常意味着在赋值操作中,你试图将一个固定长度的数组或元组赋值给由布尔索引数组指定的、可能具有不同长度的输出数组。
我有形状为m,n,3的numpy数组a和形状为m,n的mask。当我尝试设置a[mask > 0] = (255, 0, 0)时,我得到错误 ValueError: NumPy boolean array indexing assignment cannot assign3 input values to the 7401 output values where the mask is true` 如何在numpy中实现此功能?
16. array indexing的输入对象也要求是一个array,比如:x[np.array([3, 3, 1, 8])]。也可以是:x[np.array([[1,1],[2,3]])],返回一个同样维度的array。 17. 多维array的indexing比较麻烦一些,个人认为基本方法就不大直观:y[np.array([0,2,4]), np.array([0,1,2])]返回的是y[0,0],y[2...
array([[[0, 0, 0], [1, 1, 1], [2, 2, 2]], [[0, 1, 2], [0, 1, 2], [0, 1, 2]]]) 1. 2. 这对于在规则网格上评估多个维度的函数特别有用。 从磁盘读取数组 这可能是大数字组创建的最常见的情况。细节,当然,很大程度上取决于磁盘上的数据格式,因此本节只能给出如何处理各种格式...
下面用代码(详见本书代码包中的boolean_indexing.py文件)具体演示其使用方法。 1 import scipy.misc 2 import matplotlib.pyplot as plt 3 import numpy as np 4 5 face = scipy.misc.face() 6 xmax = face.shape[0] 7 ymax = face.shape[1] 8 face=face[:min(xmax,ymax),:min(xmax,ymax)] 9...
EN// 数组索引值为浮点型 // array 小数点索引值 不会增加数组长度，但是如果后面又加了array索引值...
cython.declaredeclares a typed variable in the current scope, which can be used in place of thecdeftypevar[=value]construct. This has two forms, the first as an assignment (useful as it creates a declaration in interpreted mode as well):cython.declare在现在的范围内定义了一个定型的变量,这可...
Indexing Positive Negative Boolean Fancy Complex Slicing Start / To / By New Axis View Assignment Conversion Broadcast Transpose Reshape Astype Univarsal function reduction Mathematic Arithmetic Statistic Linear Algebra Complex Image Conversion .
cython.declaredeclares a typed variable in the current scope, which can be used in place of thecdeftypevar[=value]construct. This has two forms, the first as an assignment (useful as it creates a declaration in interpreted mode as well):cython.declare在现在的范围内定义了一个定型的变量,这可...
array([[0., 0., 0.], [0., 0., 0.], [0., 0., 0.]]) print('%d bytes'%(a.size*a.itemsize)) 72 bytes 打印一个函数的帮助文档,步入numpy.add print(help(np.add)) Help on ufunc object: add = class ufunc(builtins.object) ...