raise LinAlgError(“SVD did not converge”) LinAlgError: SVD did not converge in matplotlib pca determination

问题

code :

import numpy
from matplotlib.mlab import PCA
file_name = "store1_pca_matrix.txt"
ori_data = numpy.loadtxt(file_name,dtype='float', comments='#', delimiter=None,                 converters=None, skiprows=0, usecols=None, unpack=False, ndmin=0)
result = PCA(ori_data)

this is my code. though my input matrix is devoid of the nan and inf, i do get the error stated below.

raise LinAlgError("SVD did not converge") LinAlgError: SVD did not converge

what's the problem?

回答1:

This can happen when there are inf or nan values in the data.

Use this to remove nan values:

ori_data.dropna(inplace=True)

回答2:

I know this post is old, but in case someone else encounters the same problem. @jseabold was right when he said that the problem is nan or inf and the op was probably right when he said that the data did not have nan's or inf. However, if one of the columns in ori_data has always the same value, the data will get Nans, since the implementation of PCA in mlab normalizes the input data by doing

ori_data = (ori_data - mean(ori_data)) / std(ori_data).

The solution is to do:

result = PCA(ori_data, standardize=False)

In this way, only the mean will be subtracted without dividing by the standard deviation.

回答3:

I do not have an answer to this question but I have the reproduction scenario with no nans and infs. Unfortunately the datataset is pretty large (96MB gzipped).

import numpy as np
from StringIO import StringIO
from scipy import linalg
import urllib2
import gzip

url = 'http://physics.muni.cz/~vazny/gauss/X.gz'
X = np.loadtxt(gzip.GzipFile(fileobj=StringIO(urllib2.urlopen(url).read())), delimiter=',')
linalg.svd(X, full_matrices=False)

which rise:

LinAlgError: SVD did not converge

on:

>>> np.__version__
'1.8.1'
>>> import scipy
>>> scipy.__version__
'0.10.1'

but did not raise an exception on:

>>> np.__version__
'1.8.2'
>>> import scipy
>>> scipy.__version__
'0.14.0'

回答4:

If there are no inf or NaN values, possibly that is a memory issue. Please try in a machine with higher RAM.

回答5:

Even if your data is correct, it may happen because it runs out of memory. In my case, moving from a 32-bit machine to a 64-bit machine with bigger memory solved the problem.

回答6:

Following on @c-chavez answer, what worked for me was first replacing inf and -inf to nan, then removing nan. For example:

data = data.replace(np.inf, np.nan).replace(-np.inf, np.nan).dropna()

回答7:

This may be due to the singular nature of your input datamatrix (which you are feeding to PCA)

回答8:

This happened to me when I accidentally resized an image dataset to (0, 64, 3). Try checking the shape of your dataset to see if one of the dimensions is 0.

回答9:

I am using numpy 1.11.0. If the matrix has more than 1 eigvalues equal to 0, then 'SVD did not converge' is raised.

来源：https://stackoverflow.com/questions/21827594/raise-linalgerrorsvd-did-not-converge-linalgerror-svd-did-not-converge-in-m

标签

python

matplotlib

pca