[英]How can I use purrr to match records from a lookup table?
I have this dataset 我有这个数据集
library(dplyr)
data_frame(Q1= c('AL', NA, 'TX', 'FL'), Q2=c('MN', 'CO', NA, NA), value=c(10,24,12,54))
# A tibble: 4 x 3
Q1 Q2 value
<chr> <chr> <dbl>
1 AL MN 10
2 <NA> CO 24
3 TX <NA> 12
4 FL <NA> 54
And I am trying to use purrr
to convert the values in Q1
and Q2
into full state names using a lookup table 我试图使用
purrr
使用查找表将Q1
和Q2
的值转换为完整的州名
lktState <- data_frame(abb=state.abb, name=state.name)
So far I've tried this but it doesn't work 到目前为止,我已经尝试了这个,但它没有用
data_frame(Q1= c('AL', NA, 'TX', 'FL'), Q2=c('MN', 'CO', NA, NA), value=c(10,24,12,54)) %>%
mutate_at(vars('Q1','Q2'), purrr::map(.x = ., lktState$name[match(.x, lktState$abb)]))
Error in match(.x, lktState$abb) : object '.x' not found
匹配错误(.x,lktState $ abb):找不到对象'.x'
base R version (which can be vectorized but this illustrates the concept): 基本R版本(可以进行矢量化,但这说明了这个概念):
xdf <- data.frame(
Q1= c('AL', NA, 'TX', 'FL'),
Q2 = c('MN', 'CO', NA, NA),
value = c(10, 24, 12, 54),
stringsAsFactors=FALSE
) -> xdf
xdf
## Q1 Q2 value
## 1 AL MN 10
## 2 <NA> CO 24
## 3 TX <NA> 12
## 4 FL <NA> 54
lktState <- setNames(state.name, state.abb)
xdf$Q1 <- lktState[xdf$Q1]
xdf$Q2 <- lktState[xdf$Q2]
xdf
## Q1 Q2 value
## 1 Alabama Minnesota 10
## 2 <NA> Colorado 24
## 3 Texas <NA> 12
## 4 Florida <NA> 54
"tidyverse" “tidyverse”
library(dplyr)
xdf <- data_frame(
Q1= c('AL', NA, 'TX', 'FL'),
Q2 = c('MN', 'CO', NA, NA),
value = c(10, 24, 12, 54)
) -> xdf
xdf
## # A tibble: 4 x 3
## Q1 Q2 value
## <chr> <chr> <dbl>
## 1 AL MN 10
## 2 <NA> CO 24
## 3 TX <NA> 12
## 4 FL <NA> 54
lktState <- setNames(state.name, state.abb)
mutate_at(xdf, .vars=vars(-value), .funs=funs(lktState[.]))
## # A tibble: 4 x 3
## Q1 Q2 value
## <chr> <chr> <dbl>
## 1 Alabama Minnesota 10
## 2 <NA> Colorado 24
## 3 Texas <NA> 12
## 4 Florida <NA> 54
There's no need to use "apply"-like idioms to do this basic lookup table assignment. 没有必要使用“apply”式成语来执行此基本查找表分配。
I agree with Sotos that a join is the natural way to do this. 我同意Sotos的观点,即加入是自然而然的方式。 However, your
purrr
solution is definitely fixable. 但是,您的
purrr
解决方案绝对purrr
解决。
You are missing three things, 你错过了三件事,
funs
in mutate_at
. funs
在mutate_at
。 map
functions use ~
notation for anonymous functions. map
函数使用~
表示匿名函数。 _chr
variant. _chr
variant。 . 。
mutate_at(df,
vars('Q1', 'Q2'),
funs(purrr::map_chr(.x = ., ~lktState$name[match(.x, lktState$abb)])))
Gives: 得到:
# A tibble: 4 x 3 Q1 Q2 value <chr> <chr> <dbl> 1 Alabama Minnesota 10 2 <NA> Colorado 24 3 Texas <NA> 12 4 Florida <NA> 54
df <- data_frame(Q1= c('AL', NA, 'TX', 'FL'), Q2=c('MN', 'CO', NA, NA), value=c(10,24,12,54))
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