如何修复此错误 'numpy.ndarray' 对象在下面的代码中没有属性 'append'

Question

Returns this error: 'numpy.ndarray' object has no attribute 'append'

class1 = np.array([]) #creates 2 empty arrays
class2 = np.array([])

#yhat_tr is a vector(1 column, 100 rows) = numpy.ndarray
for i in yhat_tr: 
  if i < 0:
    class1.append([i]) #insert the iten in the array class1 or class2
  else:
    class2.append([i])

I want to insert new array itens inside the class1 or class2 arrays as soon the itens are evaluated inside the loop. After that i will try to print the results in a scatter graphic with 2 colors where i can identify visually the class1 and class2 elements.

Answer 1

You can add a NumPy array element by using the append() method of the NumPy module.

The syntax of append is as follows:

numpy.append(array, value, axis)

The values will be appended at the end of the array and a new ndarray will be returned with new and old values as shown above.

The axis is an optional integer along which define how the array is going to be displayed. If the axis is not specified, the array structure will be flattened

Answer 2

A quick look at the documentation shows that np.ndarray objects do not have a function append , it is a function of np itself:

class1 = np.append(class1, [i])

Answer 3

As @Alex mentioned, numpy arrays dont have append method. You can use his suggestion to use numpy append method or You might want to define class variables as lists and use append and convert them to array after the loop as the code below does.

class1 = []
class2 = []

#yhat_tr is a vector(1 column, 100 rows) = numpy.ndarray
for i in yhat_tr: 
  if i < 0:
    class1.append([i]) #insert the iten in the array class1 or class2
  else:
    class2.append([i])

class1 = np.array(class1)
class2 = np.array(class2)

Answer 4

Love how the famous Stackoverflow is so full of judgemental posters. Making this not much better than Facebook.

You need to up your game SO.