Rifyll

| | T | F | |—|—|—| | Positive | TP | FP | | Negative | FN | TN | TP: 预测结果是Postive这个命题本身是TRUE TF: 预测结果是Negative这个命题本身是TRUE FP: 预测结果是Postive这个命题本身是FALSE FN: 预测结果是Negative这个命题本身是FALSE

Recall = TP/(TP+FN) ,所有原本是postive的样本中被正确预测到的占比

• 之所以叫Recal就是对原本情况的追溯

Precision = TP/(TP+FP), 所有被预测为Positive的样本中被正确预测的占比

• 预测结果被分为两部分，正确预测和错误预测

Accuracy = (TP+TN)/Total, 所有样本被正确预测的占比

为什么用RoC来衡量分类器（classifer）的好坏？

• 期望 最大化 True Positive 的比例，同时 最小化 False positive 的比例
• 极端情况是TPR=1， FPR=0

Configuring R to Use an HTTP or HTTPS Proxy

To set the required environment variables you should add them to the R environment file (which is read by R at startup). On RStudio Server this file is found at R_HOME/etc/Renviron.site. On RStudio Desktop this file is found in the user home directory at ~/.Renviron. You can easily access your .Renviron file by running the command file.edit('~/.Renviron') within RStudio

Note that these files might not exist in the default installation of R so you may need to create them if they aren’t already present.

http_proxy=http://proxy.dom.com/
http_proxy_user=user:passwd

https_proxy=https://proxy.dom.com/
https_proxy_user=user:passwd

how to change the default working directory

1. Navigate to ‘Rprofile.site’, open it in text-editor.
2. insert right at the top of the file in the first line the following command which tells R to set the working directory at start-up to the PATH you are specifying within the brackets (be sure you use double backslashes “\” for Windows!)

   setwd("xxxx:\\xxxx\\xxxx")
   

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