Question

这是问题的要点。如果您愿意，可以阅读代码。

我将以下命令附加两个numpy数组列表：

np.append(list1,list2)

我所期待的是输出列表长度为len（list1）+ len（list2）但相反，输出完全不同。代码已关闭..它有点长......对此有所了解。这种追加行动是否存在“陷阱”？感谢

我无法弄清楚我做错了什么？让我只是编写代码和输出..以及我期待的和我得到的东西:( 还读取输出..我已突出显示错误的位置

So I input two list and their corresponding labels.
import numpy as np
def list_appending( list_1, list_2,  y_one, y_two):
 count_1 = len(list_1)
 count_2 = len(list_2)
  #if one list is bigger than other.. then add synthetic values shorter list 
   #and its target y variable
 if count_1 > count_2:

    diff = count_1 - count_2
    new_y = np.zeros(diff)
    new_feature_list = generate_synthetic_data(list_2,diff)

    print "appended ", len(new_feature_list)," synthetic entries to first class (label0)"
elif count_2 > count_1:
    diff = count_2 - count_1
    new_feature_list = generate_synthetic_data(list_1,diff)
    new_y = np.ones(diff)
    print "appended ", len(new_feature_list)," synthetic entries to second class (label1)"
else:
    diff = 0
    new_feature_list = []
    print "nothing appended"
print "class 1 y x",len(y_one), len(list_1)
print "class 2 y x",len(y_two), len(list_2)

print "len l1 l2 ",len(list_1) , len(list_2)
f_list = np.append(list_1,list_2) # error is in this line.. unexpected.. see output
print "first x append ", len(f_list)
f_list = np.append(f_list,new_feature_list)
print "second x append ", len(f_list)
print "new features ", len(new_y), len(new_feature_list)
new_y_list =  np.append(y_one,y_two)
print "first y append ", len(new_y_list)
new_y_list = np.append(new_y_list,new_y)
print "second y append ", len(new_y_list)
# print features_list_1.shape, features_list_2.shape, new_feature_list.shapes
#print len(features_list_1[0]), len(features_list_2[0]), len(new_feature_list[0])


print "appended ", len(f_list), len(new_y_list)
return f_list, new_y_list

输出：

appended  35839  synthetic entries to first class (label0)
class 1 y x 42862 42862
class 2 y x 7023 7023
len l1 l2  42862 7023
first x append  349195 <----- This is the error line 42862 + 7023 = 49885
second x append  600068
 new features  35839 35839
first y append  49885   <------------This append was just fine..
second y append  85724
appended  600068 85724

Answer 1

来自doc page：

If axis is None, out is a flattened array.

我的猜测是你不想压扁名单。

Answer 2

您的代码非常难以理解。

在我看来，你有两个列表 - list1和list2 - 并且你想填充较短的列表以使它们具有相同的长度。要巧妙地做到这一点：

n, m = len(list1), len(list2)

if n > m:
    # Make the shorter list come first
    list1, list2 = list2, list1
    n, m = m, n

list1.append(generate_padding(m-n) if n < m else [])

列出附加奇怪的错误：python

2 个答案: