Sparse principal component analysis (SPCA) addresses the poor interpretability and variable redundancy often encountered by principal component analysis (PCA) in high-dimensional data. However, SPCA typically imposes uniform penalties on variables and does not account for differences in variable importance, which may lead to unstable performance in highly noisy or structurally complex settings. We propose SP-SPCA, a method that introduces a single equilibrium parameter into the regularization framework to adaptively adjust variable penalties. This modification of the L2 penalty provides flexible control over the trade-off between sparsity and explained variance while maintaining computational efficiency. Simulation studies show that the proposed method consistently outperforms standard sparse principal component methods in identifying sparse loading patterns, filtering noise variables, and preserving cumulative variance, especially in high-dimensional and noisy settings. Empirical applications to crime and financial market data further demonstrate its practical utility. In real data analyses, the method selects fewer but more relevant variables, thereby reducing model complexity while maintaining explanatory power. Overall, the proposed approach offers a robust and efficient alternative for sparse modeling in complex high-dimensional data, with clear advantages in stability, feature selection, and interpretability
Figures & tables
X∗=(XZ),y∗=(y0)
Algorithm 1 Coordinate Descent Algorithm for SPPCSO
PCA
SPCA
SP-SPCA
PC1
PC2
PC1
PC2
PC1
PC2
X1
-0.315
0.400
0
0.590
0
0.491
X2
-0.315
0.349
0
0.206
0
0.501
X3
-0.315
0.404
0
0.566
0
0.502
X4
-0.315
0.396
0
0.538
0
0.498
X5
0.317
0.277
0.388
0
0.499
0
Table 1: Loading matrix and explained variance for PCA, SPCA, and SP-SPCA on a low-dimensional dataset.
Parameter
Symbol
Sample size
n
Total number of variables
p
Number of latent factors
d
Variables per factor
s
Number of mixed variables
m
Table 2: Key parameter settings used in the simulation studies
PC1
PC2
PC3
PC4
PC5
X1\textendashX50
Nonzero
0
0
0
0
X51\textendashX100
0
Nonzero
0
0
0
X101\textendashX150
0
0
0
Nonzero
0
X151\textendashX200
0
0
0
0
Nonzero
X201\textendashX250
0
0
Nonzero
0
0
X251\textendashX300
0
0
0
0
0
Table 3: Case 1: Ideal Loadings Matrix Results.
Figure 5
p
150
300
450
600
750
900
SPCA
57%
56.5%
29.2%
20%
16.3%
14.4%
SP-SPCA
68.8%
65.7%
60%
56.9%
55.9%
54.6%
Table 4: Case 2: Comparison of cumulative variance explained (%) under different dimensions p .
m
10
50
100
150
SPCA
61%
56.5%
38.1%
27.2%
SP-SPCA
71.2%
65.7%
47.3%
35.3%
Table 5: Case 3: Comparison of cumulative variance explained (%) under different numbers of mixed variables m with n=100 , p=300 .
d
2
5
10
SPCA
22.4%
56.5%
44%
SP-SPCA
60%
65.7%
61.1%
Table 6: Case 4: Comparison of cumulative variance explained (%) under different numbers of latent factors d with n=100 , p=300 .
Figure 3: Comparison of numerical simulation results for high-dimensional data.
Name
Samples
Features
Type
Description
Source
Crime
1994
99
Regular
Social data
UCI
S&P 500
150
503
High-dimensional
Financial data
Kaggle
Table 7: Description of datasets used for empirical analysis
Figure 4: Cumulative explanatory rate curves and gravel plots for the Crime data.
Variance
10%
20%
30%
40%
50%
60%
70%
80%
SPCA
8
27
45
123
220
432
666
1485
SP-SPCA
14
24
40
59
104
347
644
1485
Table 8: Comparison of the total number of nonzero loadings under different cumulative variance explained levels for SPCA and SP-SPCA on the Crime dataset
Figure 5: Comparison of results for the Crime data .
Figure 6: Cumulative explanatory rate curves and gravel plots for the S&P500 data.
Variance
10%
20%
30%
40%
50%
60%
70%
80%
SPCA
16
75
209
2187
6319
9852
12856
25150
SP-SPCA
16
52
152
2002
5721
9055
12103
25150
Table 9: Comparison of the total number of nonzero loadings under different cumulative variance explained levels for SPCA and SP-SPCA
Figure 7: Comparison of results for the S&P500 data .
Principal component analysis (PCA) finds orthogonal directions of greatest variance for data compression, visualization, denoising, and feature discovery.