Python中scipy.misc.logsumexp函数的应用场景及示例代码

Python 专栏收录该内容
¥59.90 ¥99.00
211篇文章

概述:
在Python的科学计算库scipy中,有一个非常实用的函数scipy.misc.logsumexp。该函数用于计算一组数的对数和,它解决了在进行概率计算、对数似然估计等任务时常常遇到的数值稳定性问题。本文将详细介绍logsumexp函数的应用场景,并提供一些示例代码帮助读者更好地理解。

logsumexp函数的定义:
logsumexp函数的定义如下:

scipy.misc.logsumexp(a, axis=None, keepdims=False, return_sign=False)
【对数求和指数函数(log_sum_exp)】是一种常见的数学计算方法,它可以在数值稳定的情况下对大量数据进行求和运算,被广泛应用于机器学习、图像处理等领域。在... 在给出代码之前,先解释一下【对数求和指数函数】的公式:log(sum(exp(xi)))。其中exp(xi)是指数函数,sum(exp(xi))是所有指数函数的和,log()表示取对数。在上述代码中,首先使用NumPy库中的max函数找出输入数组x中的最大值xmax,然后通过将所有元素减去该最大值再求指数函数和的方式实现了【对数求和指数函数】。总之,【对数求和指数函数】是一种极为重要的数学计算方法,可以优化各种数值计算中的精度和效率,无论是对新手还是专业人士都有着重要的参考价值。 阅读详情

相关推荐

避坑指南:CesiumLab+ENVI处理Sentinel-2影像数据的完整流程

本文提供了一份详细的避坑指南,完整介绍了如何利用CesiumLab和ENVI工具链,将Sentinel-2卫星影像处理成可供Cesium三维地球引擎加载的离线瓦片数据。内容涵盖数据获取、SNAP预处理、ENVI影像增强合成以及CesiumLab切片配置等全流程实战步骤与关键参数优化,旨在帮助工程师高效构建自主可控的高精度离线地图服务。

weixin_29248653的博客 288

Windows-Anaconda3+TensorFlow安装教程

测试环境:win10-64位和win7-64位 (系统必须是64位,因为TensorFlow目前只支持64位) 一、安装Anaconda3 1.下载Anaconda3 Anaconda官网链接:link 这里我们选择Windows版本,python3.6-version-64位,如下图所示。 2.下载完成之后,点击安装Anaconda3 注意:安装过程中要选择添加环境变量,如图 待安装完成...

DoctorCuiLab的博客 3086

微信支付V2,jsapi支付拉起收银台报错:调用支付JSAPI缺少参数:total_fee

拉起收银台报错

m0_54355172的博客 3871

从jieba分词到BERT-wwm——中文自然语言处理(NLP)基础分享系列(12)

今天是本系列的最后一期,完整代码呈现Huggingface transformers平台上微调BERT-wwm-ext的过程方法。

weixin_49518391的博客 3762

Ta-Lib源码解析(三):蜡烛图指标 (Candlestick Indicator) #(附Python重构代码和示意图)(补充中)

蜡烛图指标为识别K线形态的指标,笔者认为重点在于定义方式所提供的思路,背后的投资逻辑可以借鉴但不建议直接参考文档的翻译内容和源码逻辑存在不一致的现象,笔者分别列出中文百科中的定义和源码实际逻辑,供大家参考技术分析理论中的一些模糊词,ta-lib中给出了精确的定义源码

量化就是探索生活 3253

frp内网穿透(socks隧道)

在实验过程中还是遇到了挺多的问题,但好在大多都解决了。不过还是遗留了一些不懂的问题,等以后再慢慢研究了。最后,以上仅为个人的拙见,如何有不对的地方,欢迎各位师傅指正与补充,有兴趣的师傅可以一起交流学习。

2301_76227305的博客 1万+

保姆级教程:用MATLAB复现格拉斯哥大学FMCW雷达数据集多普勒谱(附完整代码与避坑指南)

本文提供了一份详细的MATLAB教程,指导如何复现格拉斯哥大学FMCW雷达数据集的多普勒谱分析。从环境准备、数据获取到距离压缩、MTI滤波、时频分析(STFT)以及结果后处理,涵盖了完整流程,并附有优化代码和避坑指南,特别适合雷达信号处理研究者和工程师。

weixin_28720767的博客 114

【扫地机器人】详细介绍扫地机器人软硬件测试和场景化测试

本文提出2025版扫地机器人全生命周期测试方案,涵盖实验室仿真、硬件台架、客户实景等全流程验证。测试以"清洁率≥95%、覆盖率≥98%、MTBF≥1000h"为核心指标,采用数字孪生与120套真实场景结合的双V模型。重点包括:传感器精度(LDS误差<±10mm)、清洁系统性能(10g粉尘吸入率≥99%)、动力续航(800次循环容量保持≥80%)等硬件测试;以及SLAM重定位(误差<5cm)、AI识别(mAP>92%)等软件验证。方案特别针对宠物家庭(毛发缠绕率≤3%)、

2501_92897788的博客 2280

深度学习工具包 DeepLearningToolbox

深度学习工具包Deprecation notice.-----This toolbox is outdated and no longer maintained.There are much better tools available for deep learning than this toolbox, e.g. [Theano](http://deeplearning.net/software/theano/), [torch](http://torch.ch/) or [tensorflow](http://www.tensorflow.org/)I would suggest you use one of the tools mentioned above rather than use this toolbox.Best, Rasmus.DeepLearnToolbox================A Matlab toolbox for Deep Learning.Deep Learning is a new subfield of machine learning that focuses on learning deep hierarchical models of data.It is inspired by the human brain's apparent deep (layered, hierarchical) architecture.A good overview of the theory of Deep Learning theory is[Learning Deep Architectures for AI](http://www.iro.umontreal.ca/~bengioy/papers/ftml_book.pdf)For a more informal introduction, see the following videos by Geoffrey Hinton and Andrew Ng.* [The Next Generation of Neural Networks](http://www.youtube.com/watch?v=AyzOUbkUf3M) (Hinton, 2007)* [Recent Developments in Deep Learning](http://www.youtube.com/watch?v=VdIURAu1-aU) (Hinton, 2010)* [Unsupervised Feature Learning and Deep Learning](http://www.youtube.com/watch?v=ZmNOAtZIgIk) (Ng, 2011)If you use this toolbox in your research please cite [Prediction as a candidate for learning deep hierarchical models of data](http://www2.imm.dtu.dk/pubdb/views/publication_details.php?id=6284)```@MASTERSTHESIS\{IMM2012-06284, author = "R. B. Palm", title = "Prediction as a candidate for learning deep hierarchical models of data", year = "2012",}```Contact: rasmusbergpalm at gmail dot comDirectories included in the toolbox-----------------------------------`NN/` - A library for Feedforward Backpropagation Neural Networks`CNN/` - A library for Convolutional Neural Networks`DBN/` - A library for Deep Belief Networks`SAE/` - A library for Stacked Auto-Encoders`CAE/` - A library for Convolutional Auto-Encoders`util/` - Utility functions used by the libraries`data/` - Data used by the examples`tests/` - unit tests to verify toolbox is workingFor references on each library check REFS.mdSetup-----1. Download.2. addpath(genpath('DeepLearnToolbox'));Example: Deep Belief Network---------------------```matlabfunction test_example_DBNload mnist_uint8;train_x = double(train_x) / 255;test_x = double(test_x) / 255;train_y = double(train_y);test_y = double(test_y);%% ex1 train a 100 hidden unit RBM and visualize its weightsrand('state',0)dbn.sizes = [100];opts.numepochs = 1;opts.batchsize = 100;opts.momentum = 0;opts.alpha = 1;dbn = dbnsetup(dbn, train_x, opts);dbn = dbntrain(dbn, train_x, opts);figure; visualize(dbn.rbm{1}.W'); % Visualize the RBM weights%% ex2 train a 100-100 hidden unit DBN and use its weights to initialize a NNrand('state',0)%train dbndbn.sizes = [100 100];opts.numepochs = 1;opts.batchsize = 100;opts.momentum = 0;opts.alpha = 1;dbn = dbnsetup(dbn, train_x, opts);dbn = dbntrain(dbn, train_x, opts);%unfold dbn to nnnn = dbnunfoldtonn(dbn, 10);nn.activation_function = 'sigm';%train nnopts.numepochs = 1;opts.batchsize = 100;nn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.10, 'Too big error');```Example: Stacked Auto-Encoders---------------------```matlabfunction test_example_SAEload mnist_uint8;train_x = double(train_x)/255;test_x = double(test_x)/255;train_y = double(train_y);test_y = double(test_y);%% ex1 train a 100 hidden unit SDAE and use it to initialize a FFNN% Setup and train a stacked denoising autoencoder (SDAE)rand('state',0)sae = saesetup([784 100]);sae.ae{1}.activation_function = 'sigm';sae.ae{1}.learningRate = 1;sae.ae{1}.inputZeroMaskedFraction = 0.5;opts.numepochs = 1;opts.batchsize = 100;sae = saetrain(sae, train_x, opts);visualize(sae.ae{1}.W{1}(:,2:end)')% Use the SDAE to initialize a FFNNnn = nnsetup([784 100 10]);nn.activation_function = 'sigm';nn.learningRate = 1;nn.W{1} = sae.ae{1}.W{1};% Train the FFNNopts.numepochs = 1;opts.batchsize = 100;nn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.16, 'Too big error');```Example: Convolutional Neural Nets---------------------```matlabfunction test_example_CNNload mnist_uint8;train_x = double(reshape(train_x',28,28,60000))/255;test_x = double(reshape(test_x',28,28,10000))/255;train_y = double(train_y');test_y = double(test_y');%% ex1 Train a 6c-2s-12c-2s Convolutional neural network %will run 1 epoch in about 200 second and get around 11% error. %With 100 epochs you'll get around 1.2% errorrand('state',0)cnn.layers = { struct('type', 'i') %input layer struct('type', 'c', 'outputmaps', 6, 'kernelsize', 5) %convolution layer struct('type', 's', 'scale', 2) %sub sampling layer struct('type', 'c', 'outputmaps', 12, 'kernelsize', 5) %convolution layer struct('type', 's', 'scale', 2) %subsampling layer};cnn = cnnsetup(cnn, train_x, train_y);opts.alpha = 1;opts.batchsize = 50;opts.numepochs = 1;cnn = cnntrain(cnn, train_x, train_y, opts);[er, bad] = cnntest(cnn, test_x, test_y);%plot mean squared errorfigure; plot(cnn.rL);assert(er<0.12, 'Too big error');```Example: Neural Networks---------------------```matlabfunction test_example_NNload mnist_uint8;train_x = double(train_x) / 255;test_x = double(test_x) / 255;train_y = double(train_y);test_y = double(test_y);% normalize[train_x, mu, sigma] = zscore(train_x);test_x = normalize(test_x, mu, sigma);%% ex1 vanilla neural netrand('state',0)nn = nnsetup([784 100 10]);opts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samples[nn, L] = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.08, 'Too big error');%% ex2 neural net with L2 weight decayrand('state',0)nn = nnsetup([784 100 10]);nn.weightPenaltyL2 = 1e-4; % L2 weight decayopts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samplesnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex3 neural net with dropoutrand('state',0)nn = nnsetup([784 100 10]);nn.dropoutFraction = 0.5; % Dropout fraction opts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samplesnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex4 neural net with sigmoid activation functionrand('state',0)nn = nnsetup([784 100 10]);nn.activation_function = 'sigm'; % Sigmoid activation functionnn.learningRate = 1; % Sigm require a lower learning rateopts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samplesnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex5 plotting functionalityrand('state',0)nn = nnsetup([784 20 10]);opts.numepochs = 5; % Number of full sweeps through datann.output = 'softmax'; % use softmax outputopts.batchsize = 1000; % Take a mean gradient step over this many samplesopts.plot = 1; % enable plottingnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex6 neural net with sigmoid activation and plotting of validation and training error% split training data into training and validation datavx = train_x(1:10000,:);tx = train_x(10001:end,:);vy = train_y(1:10000,:);ty = train_y(10001:end,:);rand('state',0)nn = nnsetup([784 20 10]); nn.output = 'softmax'; % use softmax outputopts.numepochs = 5; % Number of full sweeps through dataopts.batchsize = 1000; % Take a mean gradient step over this many samplesopts.plot = 1; % enable plottingnn = nntrain(nn, tx, ty, opts, vx, vy); % nntrain takes validation set as last two arguments (optionally)[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');```[![Bitdeli Badge](https://d2weczhvl823v0.cloudfront.net/rasmusbergpalm/deeplearntoolbox/trend.png)](https://bitdeli.com/free "Bitdeli Badge")

Camera2Demo

在Camera2 的基础上进行封装,使得Camera2一堆初始化逻辑与Activity分离,降低耦合度,完成预览拍照并保存的操作

计算机控制技术及应用

《计算机控制技术及应用》通过总结作者的科研成果和吸收国内外的先进理论、方法和技术,以计算机控制系统的网络化、开放化、智能化和集成化发展趋势为主线索,主要介绍计算机控制系统的基本概念和计算机控制系统的典型形式,计算机控制系统的数学描述与基本分析方法,以及数字PID控制器、最少拍控制系统、达林算法、状态变量设计法等设计方法及其各种改进算法。重点突出计算机控制系统输入输出通道接口的设计方法和典型控制系统的设计案例与实现方法等。

NTscan扫描工具

ntscan是一个扫描器,可以扫描没有密码和弱密码的共享,先到配置文件中填写猜测的用户名和密码,扫描过程中右侧出现的是扫描日志。

上一篇: 基于布谷鸟算法优化支持向量机(SVM)实现数据分类
下一篇: Python PGPKey.parse方法代码示例
普通网友
博客等级 码龄3年 341粉丝 659原创
评论
成就一亿技术人!
拼手气红包6.0元
还能输入1000个字符  | 博主筛选后可见
 
 条评论被折叠 查看
添加红包

请填写红包祝福语或标题

个

红包个数最小为10个

元

红包金额最低5元

当前余额3.43元 前往充值 >
需支付:10.00元
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付元
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值