R中有字典功能吗 [英] Is there a dictionary functionality in R
问题描述
有没有一种方法可以在R中创建字典",使其具有成对的? 可以起到以下作用的
Is there a way to create a "dictionary" in R, such that it has pairs? Something to the effect of:
x=dictionary(c("Hi","Why","water") , c(1,5,4))
x["Why"]=5
我之所以问这个,是因为我实际上正在寻找两个类别变量函数.
I'm asking this because I am actually looking for a two categorial variables function.
因此,如果x = dictionary(c("a","b"),c(5,2))
So that if x=dictionary(c("a","b"),c(5,2))
x val
1 a 5
2 b 2
我想在x键的所有组合上计算x1 ^ 2 + x2
I want to compute x1^2+x2 on all combinations of x keys
x1 x2 val1 val2 x1^2+x2
1 a a 5 5 30
2 b a 2 5 9
3 a b 5 2 27
4 b b 2 2 6
然后我希望能够使用x1和x2检索结果.效果: get_result ["b","a"] = 9
And then I want to be able to retrieve the result using x1 and x2. Something to the effect of: get_result["b","a"] = 9
什么是最好,最有效的方法?
what is the best, efficient way to do this?
推荐答案
我知道字典的三个R包:hash
,hashmap
和dict
.
I know three R packages for dictionaries: hash
, hashmap
, and dict
.
2018年7月更新: :一个新的 2018年9月更新: :一个新的键必须是字符串.值可以是任何R对象.
Keys must be character strings. A value can be any R object.
library(hash)
## hash-2.2.6 provided by Decision Patterns
h <- hash()
# set values
h[["1"]] <- 42
h[["foo"]] <- "bar"
h[["4"]] <- list(a=1, b=2)
# get values
h[["1"]]
## [1] 42
h[["4"]]
## $a
## [1] 1
##
## $b
## [1] 2
h[c("1", "foo")]
## <hash> containing 2 key-value pair(s).
## 1 : 42
## foo : bar
h[["key not here"]]
## NULL
要获取密钥:
keys(h)
## [1] "1" "4" "foo"
要获取值:
values(h)
## $`1`
## [1] 42
##
## $`4`
## $`4`$a
## [1] 1
##
## $`4`$b
## [1] 2
##
##
## $foo
## [1] "bar"
print
实例:
h
## <hash> containing 3 key-value pair(s).
## 1 : 42
## 4 : 1 2
## foo : bar
values
函数接受sapply
的参数:
values(h, USE.NAMES=FALSE)
## [[1]]
## [1] 42
##
## [[2]]
## [[2]]$a
## [1] 1
##
## [[2]]$b
## [1] 2
##
##
## [[3]]
## [1] "bar"
values(h, keys="4")
## 4
## a 1
## b 2
values(h, keys="4", simplify=FALSE)
## $`4`
## $`4`$a
## [1] 1
##
## $`4`$b
## [1] 2
哈希图
请参见 https://cran.r-project.org/web /packages/hashmap/README.html .
hashmap
不提供 not 来提供存储任意类型对象的灵活性.
hashmap
does not offer the flexibility to store arbitrary types of objects.
键和值仅限于标量"对象(长度为1的字符,数字等).这些值必须是相同的类型.
Keys and values are restricted to "scalar" objects (length-one character, numeric, etc.). The values must be of the same type.
library(hashmap)
H <- hashmap(c("a", "b"), rnorm(2))
H[["a"]]
## [1] 0.1549271
H[[c("a","b")]]
## [1] 0.1549271 -0.1222048
H[[1]] <- 9
美丽的print
实例:
H
## ## (character) => (numeric)
## ## [1] => [+9.000000]
## ## [b] => [-0.122205]
## ## [a] => [+0.154927]
错误:
H[[2]] <- "Z"
## Error in x$`[[<-`(i, value): Not compatible with requested type: [type=character; target=double].
H[[2]] <- c(1,3)
## Warning in x$`[[<-`(i, value): length(keys) != length(values)!
dict
当前仅在Github上可用: https://github.com/mkuhn/dict
优势:任意键和值,并且快速.
Strengths: arbitrary keys and values, and fast.
library(dict)
d <- dict()
d[[1]] <- 42
d[[c(2, 3)]] <- "Hello!" # c(2,3) is the key
d[["foo"]] <- "bar"
d[[4]] <- list(a=1, b=2)
d[[1]]
## [1] 42
d[[c(2, 3)]]
## [1] "Hello!"
d[[4]]
## $a
## [1] 1
##
## $b
## [1] 2
访问不存在的密钥会引发错误:
Accessing to a non-existing key throws an error:
d[["not here"]]
## Error in d$get_or_stop(key): Key error: [1] "not here"
但是有一个很好的功能可以解决:
But there is a nice feature to deal with that:
d$get("not here", "default value for missing key")
## [1] "default value for missing key"
获取密钥:
d$keys()
## [[1]]
## [1] 4
##
## [[2]]
## [1] 1
##
## [[3]]
## [1] 2 3
##
## [[4]]
## [1] "foo"
获取值:
d$values()
## [[1]]
## [1] 42
##
## [[2]]
## [1] "Hello!"
##
## [[3]]
## [1] "bar"
##
## [[4]]
## [[4]]$a
## [1] 1
##
## [[4]]$b
## [1] 2
获取物品:
d$items()
## [[1]]
## [[1]]$key
## [1] 4
##
## [[1]]$value
## [[1]]$value$a
## [1] 1
##
## [[1]]$value$b
## [1] 2
##
##
##
## [[2]]
## [[2]]$key
## [1] 1
##
## [[2]]$value
## [1] 42
##
##
## [[3]]
## [[3]]$key
## [1] 2 3
##
## [[3]]$value
## [1] "Hello!"
##
##
## [[4]]
## [[4]]$key
## [1] "foo"
##
## [[4]]$value
## [1] "bar"
没有print
实例.
该软件包还提供了功能numvecdict
来处理字典,在字典中数字和字符串(包括每个向量)可以用作键,并且只能存储数字向量.
The package also provides the function numvecdict
to deal with a dictionary in which numbers and strings (including vectors of each) can be used as keys, and that can only store vectors of numbers.
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