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汕头大学海洋科学接受调剂
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一笑35

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[交流] 【求助/交流】虫虫们,有没有做PCA主成分分析的啊? 已有12人参与

各位虫虫们,有没有做PCA主成分分析的啊,一般是用什么软件呢,有可以免费下载的网址吗?
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sqhnsd

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引用回帖:
Originally posted by 一笑35 at 2010-08-25 09:12:36:
各位虫虫们,有没有做PCA主成分分析的啊,一般是用什么软件呢,有可以免费下载的网址吗?

大名鼎鼎的R软件业可以做,不过需要自己去学习,关键R是免费的
5楼2010-08-25 10:55:13
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yanruoke

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请问分析对象具体是?
戒嗔怒以养肝气,省言语以养神气,多读书以养质气,顺时令以养元气,不拘节以养大气,观天变以养灵气,莫强求规于运气。
2楼2010-08-25 09:18:13
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reasonspare

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silicare(金币+2):专家级~ 2010-08-25 12:28:28
引用回帖:
Originally posted by 一笑35 at 2010-08-25 09:12:36:
各位虫虫们,有没有做PCA主成分分析的啊,一般是用什么软件呢,有可以免费下载的网址吗?

最经典的是用SAS得princomp过程。另来SAS 得的主因子分析 Factor 因不错。
此外SPSS.也不错。其他的诸如


Metlab,也有现成的命令

princomp - Principal component analysis on data
Syntax

[COEFF,SCORE] = princomp(X)
[COEFF,SCORE,latent] = princomp(X)
[COEFF,SCORE,latent,tsquare] = princomp(X)
[...] = princomp(X,'econ')
Description

COEFF = princomp(X) performs principal components analysis on the n-by-p data matrix X, and returns the principal component coefficients, also known as loadings. Rows of X correspond to observations, columns to variables. COEFF is a p-by-p matrix, each column containing coefficients for one principal component. The columns are in order of decreasing component variance.

princomp centers X by subtracting off column means, but does not rescale the columns of X. To perform principal components analysis with standardized variables, that is, based on correlations, use princomp(zscore(X)). To perform principal components analysis directly on a covariance or correlation matrix, use pcacov.

[COEFF,SCORE] = princomp(X) returns SCORE, the principal component scores; that is, the representation of X in the principal component space. Rows of SCORE correspond to observations, columns to components.

[COEFF,SCORE,latent] = princomp(X) returns latent, a vector containing the eigenvalues of the covariance matrix of X.

[COEFF,SCORE,latent,tsquare] = princomp(X) returns tsquare, which contains Hotelling's T2 statistic for each data point.

The scores are the data formed by transforming the original data into the space of the principal components. The values of the vector latent are the variance of the columns of SCORE. Hotelling's T2 is a measure of the multivariate distance of each observation from the center of the data set.

When n <= p, SCORE(:,n:p) and latent(n:p) are necessarily zero, and the columns of COEFF(:,n:p) define directions that are orthogonal to X.

[...] = princomp(X,'econ') returns only the elements of latent that are not necessarily zero, and the corresponding columns of COEFF and SCORE, that is, when n <= p, only the first n-1. This can be significantly faster when p is much larger than n.
Examples

Compute principal components for the ingredients data in the Hald data set, and the variance accounted for by each component.

load hald;
[pc,score,latent,tsquare] = princomp(ingredients);
pc,latent

pc =
  0.0678 -0.6460  0.5673 -0.5062
  0.6785 -0.0200 -0.5440 -0.4933
-0.0290  0.7553  0.4036 -0.5156
-0.7309 -0.1085 -0.4684 -0.4844

latent =
517.7969
  67.4964
  12.4054
   0.2372

The following command and plot show that two components account for 98% of the variance:

cumsum(latent)./sum(latent)
ans =
      0.86597
      0.97886
       0.9996
            1
biplot(pc(:,1:2),'Scores',score(:,1:2),'VarLabels',...
                {'X1' 'X2' 'X3' 'X4'})


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3楼2010-08-25 09:59:53
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一笑35

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我是用来做DGGE的PCA主成分分析的,可以从较官方网上免费下载吗?
努力学习,充实自己!
4楼2010-08-25 10:54:10
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