Contractive autoencoder

  • 文章类型: Journal Article
    对股票市场的准确预测对于股票市场的投资者和其他利益相关者制定有利可图的投资策略非常重要。即使有轻微的边际,预测模型准确性的提高也可以转化为可观的货币回报。然而,股市预测被认为是一个复杂的噪声研究问题,股票数据的复杂性和波动性。近年来,深度学习模型已经成功地为顺序数据提供了可靠的预测。我们通过将窥视孔LSTM与时间注意力层(TAL)相结合,提出了一种基于深度学习的混合分类模型,以准确预测股票市场的方向。包括美国在内的四个世界指数的每日数据,英国,中国和印度,从2005年到2022年,进行了检查。我们通过初步数据分析进行了全面评估,股市预测问题的特征提取和超参数优化。后窥视孔LSTM引入了TAL,以选择有关时间的相关信息并增强所提出模型的性能。将该模型的预测性能与基准模型CNN的预测性能进行了比较,LSTM,SVM和RF使用精度评估指标,精度,召回,F1分数,AUC-ROC,PR-AUC和MCC。实验结果表明,对于大多数评估指标和所有数据集,我们提出的模型的性能优于基准模型。该模型对英国和中国股市的准确率分别为96%和88%,对美国和印度股市的准确率为85%。因此,英国和中国的股市比美国和印度的股市更可预测。我们工作的重要发现包括注意层使窥视孔LSTM能够更好地识别股票市场数据中的长期依赖性和时间模式。可以根据我们提出的预测模型制定有利可图的及时交易策略。
    Accurate predictions of stock markets are important for investors and other stakeholders of the equity markets to formulate profitable investment strategies. The improved accuracy of a prediction model even with a slight margin can translate into considerable monetary returns. However, the stock markets\' prediction is regarded as an intricate research problem for the noise, complexity and volatility of the stocks\' data. In recent years, the deep learning models have been successful in providing robust forecasts for sequential data. We propose a novel deep learning-based hybrid classification model by combining peephole LSTM with temporal attention layer (TAL) to accurately predict the direction of stock markets. The daily data of four world indices including those of U.S., U.K., China and India, from 2005 to 2022, are examined. We present a comprehensive evaluation with preliminary data analysis, feature extraction and hyperparameters\' optimization for the problem of stock market prediction. TAL is introduced post peephole LSTM to select the relevant information with respect to time and enhance the performance of the proposed model. The prediction performance of the proposed model is compared with that of the benchmark models CNN, LSTM, SVM and RF using evaluation metrics of accuracy, precision, recall, F1-score, AUC-ROC, PR-AUC and MCC. The experimental results show the superior performance of our proposed model achieving better scores than the benchmark models for most evaluation metrics and for all datasets. The accuracy of the proposed model is 96% and 88% for U.K. and Chinese stock markets respectively and it is 85% for both U.S. and Indian markets. Hence, the stock markets of U.K. and China are found to be more predictable than those of U.S. and India. Significant findings of our work include that the attention layer enables peephole LSTM to better identify the long-term dependencies and temporal patterns in the stock markets\' data. Profitable and timely trading strategies can be formulated based on our proposed prediction model.
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  • 文章类型: Journal Article
    单细胞测序技术被广泛用于发现细胞的进化关系和差异。由于退出事件可能会阻碍分析,在之前的尝试中已经出现了许多单细胞RNA-seq数据的插补方法.然而,以前的估算尝试通常会遇到过于平滑的问题,这可能会给单细胞RNA-seq数据的下游分析带来有限的改善或负面影响。为了解决这个困难,本文提出了一种新的两阶段扩散去噪方法,称为SCDD,用于大规模单细胞RNA-seq填补。我们引入了扩散,即使用相似细胞表达潜在脱落位点的直接插补策略,首先进行最初的估算。扩散之后,开发了一种结合图卷积神经网络和收缩自编码器的联合模型,以生成相似细胞的叠加状态,从中我们恢复原始状态并去除扩散引入的噪声。实验结果表明,SCDD能有效抑制超平滑问题,显著提高单细胞RNA-seq下游分析的效果,包括聚类和轨迹分析。
    Single-cell sequencing technologies are widely used to discover the evolutionary relationships and the differences in cells. Since dropout events may frustrate the analysis, many imputation approaches for single-cell RNA-seq data have appeared in previous attempts. However, previous imputation attempts usually suffer from the over-smooth problem, which may bring limited improvement or negative effect for the downstream analysis of single-cell RNA-seq data. To solve this difficulty, we propose a novel two-stage diffusion-denoising method called SCDD for large-scale single-cell RNA-seq imputation in this paper. We introduce the diffusion i.e. a direct imputation strategy using the expression of similar cells for potential dropout sites, to perform the initial imputation at first. After the diffusion, a joint model integrated with graph convolutional neural network and contractive autoencoder is developed to generate superposition states of similar cells, from which we restore the original states and remove the noise introduced by the diffusion. The final experimental results indicate that SCDD could effectively suppress the over-smooth problem and remarkably improve the effect of single-cell RNA-seq downstream analysis, including clustering and trajectory analysis.
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