R -- 体验 stringdist

文章目录

  • 安装
  • 使用
    • [stringdist :返回列表](#stringdist :返回列表)
    • [stringdistmatrix :返回矩阵](#stringdistmatrix :返回矩阵)
  • [amatch & ain](#amatch & ain)
  • 延伸:距离计算公式
      • [Hamming distance](#Hamming distance)
      • [Longest Common Substring distance](#Longest Common Substring distance)
      • [Levenshtein distance (weighted)](#Levenshtein distance (weighted))
      • [The optimal string alignment distance dosa](#The optimal string alignment distance dosa)
      • [Full Damerau-Levenshtein distance (weighted)](#Full Damerau-Levenshtein distance (weighted))
      • [Q-gram distance](#Q-gram distance)
      • [Jaccard distance for q-gram count vectors (= 1-Jaccard similarity)](#Jaccard distance for q-gram count vectors (= 1-Jaccard similarity))
      • [cosine distance for q-gram count vectors (= 1-cosine similarity)](#cosine distance for q-gram count vectors (= 1-cosine similarity))
    • [At last](#At last)

安装

R 复制代码
install.packages('stringdist')

or

bash 复制代码
git clone https://github.com/markvanderloo/stringdist.git
cd stringdist
bash ./build.bash
R CMD INSTALL output/stringdist_*.tar.gz

使用

The package offers the following main functions:

  • stringdist computes pairwise distances between two input character vectors (shorter one is recycled)
  • stringdistmatrix computes the distance matrix for one or two vectors
  • stringsim computes a string similarity between 0 and 1, based on stringdist
  • amatch is a fuzzy matching equivalent of R's native match function
  • ain is a fuzzy matching equivalent of R's native %in% operator
  • afind finds the location of fuzzy matches of a short string in a long string.
  • seq_dist, seq_distmatrix, seq_amatch and seq_ain for distances between, and matching of integer sequences.

stringdist :返回列表

stringdist(
  a,
  b,
  method = c("osa", "lv", "dl", "hamming", "lcs", "qgram", "cosine", "jaccard", "jw",
    "soundex"),
  useBytes = FALSE,
  weight = c(d = 1, i = 1, s = 1, t = 1),
  q = 1,
  p = 0,
  bt = 0,
  nthread = getOption("sd_num_thread")
)

a	:R object (target); will be converted by as.characte
b	 :R object (source); will be converted by as.character This argument is optional for stringdistmatrix (see section Value).
method	 :Method for distance calculation. 
useBytes	:Perform byte-wise comparison
weight	:For method='osa' or 'dl', the penalty for deletion, insertion, substitution and transposition, in that order. 
	 When method='lv', the penalty for transposition is ignored.
	 When method='jw', the weights associated with characters of a, characters from b and the transposition weight, in that order. 
	 Weights must be positive and not exceed 1. 
	 weight is ignored completely when method='hamming', 'qgram', 'cosine', 'Jaccard', 'lcs', or soundex.

q	:Size of the q-gram; must be nonnegative. Only applies to method='qgram', 'jaccard' or 'cosine'.
p	:Prefix factor for Jaro-Winkler distance. The valid range for p is 0 <= p <= 0.25.
	 If p=0 (default), the Jaro-distance is returned. Applies only to method='jw'.
bt	:Winkler's boost threshold. Winkler's prefix factor is only applied when the Jaro distance is larger than bt. Applies only to method='jw' and p>0.
useNames	:Use input vectors as row and column names?

example

注意:String distance functions have two possible special output values.

NA is returned whenever at least one of the input strings to compare is NA .

And Inf is returned when the distance between two strings is undefined according to the selected algorithm.

R 复制代码
stringdist("bar","foo",method = "lv") #使用的是Levenshtein distance  & return  3
stringdist("ba","foo",method = "lv") #使用的是Levenshtein distance  &  return  3 ,注意这里是不等长的序列

stringdist('fu', 'foo', method='hamming') # 使用的是 Hamming distance &  return Inf

stringdistmatrix :返回矩阵

stringdistmatrix(
  a,
  b,
  method = c("osa", "lv", "dl", "hamming", "lcs", "qgram", "cosine", "jaccard", "jw",
    "soundex"),
  useBytes = FALSE,
  weight = c(d = 1, i = 1, s = 1, t = 1),
  q = 1,
  p = 0,
  bt = 0,
  useNames = c("none", "strings", "names"),
  nthread = getOption("sd_num_thread")
)
Arg

example

- 只输入一个vertor:返回一个 dist函数的结果
- 输入两个vector :返回矩阵

amatch & ain

  • Function amatch(x,table) finds the closest match of elements of x in table. When multiple equivalent matches are found, the
    first match is returned
  • A call to ain(x,table) returns a logical vector indicating which elements of x were (approximately) matched in table.
  • Both amatch and ain have been designed to approach the behaviour of R's native match and %in% functionality as much as possible. By default amatch and ain locate exact matches, just like match.
  • This may be changed by increasing the maximum string distance between the search pattern and elements of the lookup table.

amatch仿照R base function match进行设计,通过 参数maxDist控制该函数的行为,如果maxDist 设置的很小其表现近似于 exact match,当 maxDist 设置的比较大时则表现的是approximately match。amtch 与 ain的区别类似于match和 %in%,一个返回元素的index,一个返回TRUE/FALSE。

R 复制代码
amatch('fu', c('foo','bar')) # return NA
amatch('fu', c('foo','bar'), maxDist=2) # return 1

ain('fu', c('foo','bar')) # return FALSE
ain('fu', c('foo','bar'), maxDist=2) # return  TRUE
ain('bar', c('foo','bar')) # return TRUE
ain('bar', c('foo','bar'), maxDist=2) # return TRUE

延伸:距离计算公式

Hamming distance


Longest Common Substring distance



Levenshtein distance (weighted)


The optimal string alignment distance dosa

Full Damerau-Levenshtein distance (weighted)



注意,D~osa~ 和D~dl~的区别主要是最后一个方程式,D~osa~只允许前后相邻的两个字符串置换,D~dl~则允许当前的字符串和其他的字符置换后计算距离



Q-gram distance

Jaccard distance for q-gram count vectors (= 1-Jaccard similarity)

cosine distance for q-gram count vectors (= 1-cosine similarity)

  • Jaro distance

At last

相关推荐
让学习成为一种生活方式3 小时前
R包下载太慢安装中止的解决策略-R语言003
java·数据库·r语言
有梦想的Frank博士1 天前
R语言*号标识显著性差异判断组间差异是否具有统计意义
开发语言·信息可视化·r语言
逆风远航4 天前
R语言贝叶斯:INLA下的贝叶斯回归、生存分析、随机游走、广义可加模型、极端数据的贝叶斯分析
开发语言·r语言·贝叶斯·生态学·结构方程·环境科学·混合效应
Faxxtty4 天前
【R语言】解决package ‘qvalue’ is not available (for R version 3.6.1)
开发语言·r语言
Cachel wood5 天前
Vue前端框架:Vue前端项目文件目录
java·前端·vue.js·python·算法·r语言·前端框架
邢博士谈科教6 天前
OmicsTools软件和R语言分析环境安装配置答疑汇总最新版
r语言
纪伊路上盛名在6 天前
vscode中提升效率的插件扩展——待更新
linux·服务器·ide·vscode·python·r语言·编辑器
拓端研究室TRL6 天前
银行信贷风控专题:Python、R 语言机器学习数据挖掘应用实例合集:xgboost、决策树、随机森林、贝叶斯等...
python·决策树·机器学习·数据挖掘·r语言
在在进步6 天前
R数据结构&向量基础
数据结构·r语言
琼火hu8 天前
R语言笔记(五):Apply函数
开发语言·笔记·r语言·apply