PCA：类型错误：只能将列表(不能连接"int")连接到列表

Question

我试着按照这篇文章建议的解决方案在我的数据集上安装一个PCA。代码适用于形状为(150, 8)的iris数据，它看起来像这样:

array([[ 1.7837721 , -1.23464679,  4.27808537, ...,  0.63061657,
-1.79849625, -1.41574397],
[-0.35396307, -0.13400175,  3.91751182, ..., -0.58928302,
-0.15735542, -0.99157312],
[-0.20380491, -1.06074392,  4.65814864, ...,  2.19686369,
0.14920164,  2.33371106],
...,
[-1.05079672,  1.46836264,  5.41970214, ...,  0.32847349,
0.27133141,  1.01266607],
[ 0.19569856,  0.57739573,  3.84749973, ...,  0.02400556,
-0.08193678,  0.51223263],
[ 0.04905765,  0.66314259,  6.22608157, ...,  0.60076934,
-0.56890579, -0.23642103]])

然而，使用我的形状(3475, 29)的数据，它捕获错误:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-292-5661ffbde57b> in <module>
38 # data = array([randn(8) for k in range(150)])
39 data[:50, 2:4] += 5
---> 40 data[50:, 2:5] += 5
41 
42 """ visualize """
TypeError: can only concatenate list (not "int") to list

我的数据(形状(3475, 29))看起来像这样:

array([[58.5, 27.0, 88.5, ..., nan, 0.0, -3.0],
[58.5, 27.0, 88.5, ..., nan, 0.0, -3.0],
[47.0, 45.0, 92.0, ..., 1.6, -0.649519052838329,
-1.1249999999999998],
...,
[46.0, 44.5, 98.0, ..., 2.5, 0.0, -1.3],
[46.0, 40.0, 98.0, ..., 2.5, 0.0, -1.3],
[46.5, 44.5, 76.5, ..., 17.767857142857142, -0.4788774197473401,
-1.4219984343829701]], dtype=object)

代码:

# SO - doug - my data 
from numpy import array, dot, mean, std, empty, argsort
from numpy.linalg import eigh, solve
from numpy.random import randn
from matplotlib.pyplot import subplots, show

def cov(X):
"""
Covariance matrix
note: specifically for mean-centered data
note: numpy's `cov` uses N-1 as normalization
"""
return dot(X.T, X) / X.shape[0]
# N = data.shape[1]
# C = empty((N, N))
# for j in range(N):
#   C[j, j] = mean(data[:, j] * data[:, j])
#   for k in range(j + 1, N):
#       C[j, k] = C[k, j] = mean(data[:, j] * data[:, k])
# return C
def pca(data, pc_count = None):
"""
Principal component analysis using eigenvalues
note: this mean-centers and auto-scales the data (in-place)
"""
data -= mean(data, 0)
data /= std(data, 0)
C = cov(data)
E, V = eigh(C)
key = argsort(E)[::-1][:pc_count]
E, V = E[key], V[:, key]
U = dot(data, V)  # used to be dot(V.T, data.T).T
return U, E, V
""" test data """
# data = array([randn(8) for k in range(150)])
data = my_data1   # Using my own data
data[:50, 2:4] += 5
data[50:, 2:5] += 5
""" visualize """
trans = pca(data, 3)[0]
fig, (ax1, ax2) = subplots(1, 2)
ax1.scatter(data[:50, 0], data[:50, 1], c = 'r')
ax1.scatter(data[50:, 0], data[50:, 1], c = 'b')
ax2.scatter(trans[:50, 0], trans[:50, 1], c = 'r')
ax2.scatter(trans[50:, 0], trans[50:, 1], c = 'b')
show()

什么

data[:50, 2:4] += 5
data[50:, 2:5] += 5

做什么?

我试着用

替换这两行

data = [data[:50, 2:4] += 5]
data = [data[50:, 2:5] += 5]

，返回

File "<ipython-input-296-5d80e1852b4e>", line 42
data = [data[:50, 2:4] += 5]
^
SyntaxError: invalid syntax

任何建议感谢!

Answer 1

如果data是2d数字数组，

data[:50, 2:4]

选择数组的一个切片(技术上是view)，

data[:50, 2:4] += 5

将该切片的所有元素加5，并修改data。

,

TypeError: can only concatenate list (not "int") to list

表示data包含一个或多个列表，而不仅仅是数字。对于列表，+不是(数学)加法，而是连接/连接。[1,2,3]+[4].

关于你的第二次尝试:

[data[:50, 2:4] += 5]

与

非常不同

[i + 1]

[]生成一个列表。不能在列表中执行赋值操作，例如=或+=。因此出现了语法错误。

显示的(3475,29)数组将dtype列为object。这是一个强有力的指示，它包含数字以外的东西(或除了)。根据错误，它必须是一个列表。

所以你需要清理mydata。