R dplyr:使用字符串函数重命名变量

Question

(有些相关的问题:在dplyr的重命名函数中输入新的列名作为字符串)

在dplyrchain(%>%)的中间,我想用旧名称的函数替换多个列名(使用tolower或gsub等)

library(tidyr); library(dplyr)
data(iris)
# This is what I want to do, but I'd like to use dplyr syntax
names(iris) <- tolower( gsub("\\.", "_", names(iris) ) )
glimpse(iris, 60)
# Observations: 150
# Variables:
#   $ sepal_length (dbl) 5.1, 4.9, 4.7, 4.6, 5.0, 5.4, 4.6,...
#   $ sepal_width  (dbl) 3.5, 3.0, 3.2, 3.1, 3.6, 3.9, 3.4,...
#   $ petal_length (dbl) 1.4, 1.4, 1.3, 1.5, 1.4, 1.7, 1.4,...
#   $ petal_width  (dbl) 0.2, 0.2, 0.2, 0.2, 0.2, 0.4, 0.3,...
#   $ species      (fctr) setosa, setosa, setosa, setosa, s...

# the rest of the chain:
iris %>% gather(measurement, value, -species) %>%
  group_by(species,measurement) %>%
  summarise(avg_value = mean(value)) 

我认为?rename把论点replace作为一个named character vector, with new names as values, and old names as names.

所以我尝试过:

iris %>% rename(replace=c(names(iris)=tolower( gsub("\\.", "_", names(iris) ) )  ))

但是这个(a)返回Error: unexpected '=' in iris %>% ...,(b)需要通过名称引用链中先前操作的数据框,在我的实际用例中我不能这样做.

iris %>% 
  rename(replace=c(    )) %>% # ideally the fix would go here
  gather(measurement, value, -species) %>%
  group_by(species,measurement) %>%
  summarise(avg_value = mean(value)) # I realize I could mutate down here 
                                     #  instead, once the column names turn into values, 
                                     #  but that's not the point
# ---- Desired output looks like: -------
# Source: local data frame [12 x 3]
# Groups: species
# 
#       species  measurement avg_value
# 1      setosa sepal_length     5.006
# 2      setosa  sepal_width     3.428
# 3      setosa petal_length     1.462
# 4      setosa  petal_width     0.246
# 5  versicolor sepal_length     5.936
# 6  versicolor  sepal_width     2.770
# ... etc ....  

Answer 1

这是一个非常晚的答案,2017年5月

从dplyr 0.5.0.9004即将推出的0.6.0开始,许多新的重命名列方法(与maggritr管道操作符一致%>%)已添加到包中.

这些功能是:

• rename_all
• rename_if
• rename_at

使用这些功能的方法有很多种,但与您的问题相关的方法stringr有以下几种:

df <- df %>%
  rename_all(
      funs(
        stringr::str_to_lower(.) %>%
        stringr::str_replace_all(., '\\.', '_')
      )
  )

所以,继续使用管道:)(没有双关语意).

Answer 2

我认为你正在查看文档plyr::rename,而不是dplyr::rename.你会做这样的事情dplyr::rename:

iris %>% rename_(.dots=setNames(names(.), tolower(gsub("\\.", "_", names(.)))))

Answer 3

这是一种绕过有点尴尬的rename语法的方法:

myris <- iris %>% setNames(tolower(gsub("\\.","_",names(.))))

Answer 4

对于这个特殊[但相当普遍]的情况,该函数已经写在janitor包中:

library(janitor)

iris %>% clean_names()

##   sepal_length sepal_width petal_length petal_width species
## 1          5.1         3.5          1.4         0.2  setosa
## 2          4.9         3.0          1.4         0.2  setosa
## 3          4.7         3.2          1.3         0.2  setosa
## 4          4.6         3.1          1.5         0.2  setosa
## 5          5.0         3.6          1.4         0.2  setosa
## 6          5.4         3.9          1.7         0.4  setosa
## .          ...         ...          ...         ...     ...

所以在一起,

iris %>% 
    clean_names() %>%
    gather(measurement, value, -species) %>%
    group_by(species,measurement) %>%
    summarise(avg_value = mean(value))

## Source: local data frame [12 x 3]
## Groups: species [?]
## 
##       species  measurement avg_value
##        <fctr>        <chr>     <dbl>
## 1      setosa petal_length     1.462
## 2      setosa  petal_width     0.246
## 3      setosa sepal_length     5.006
## 4      setosa  sepal_width     3.428
## 5  versicolor petal_length     4.260
## 6  versicolor  petal_width     1.326
## 7  versicolor sepal_length     5.936
## 8  versicolor  sepal_width     2.770
## 9   virginica petal_length     5.552
## 10  virginica  petal_width     2.026
## 11  virginica sepal_length     6.588
## 12  virginica  sepal_width     2.974

Answer 5

我使用base,stringr和dplyr的雄辩尝试:

编辑:库(tidyverse)现在包括所有三个库.

library(tidyverse)
library(maggritr) # Though in tidyverse to use %>% pipe you need to call it 
# library(dplyr)
# library(stringr)
# library(maggritr)

names(iris) %<>% # pipes so that changes are apply the changes back
    tolower() %>%
    str_replace_all(".", "_")

我这样做是为了用管道来构建功能.

my_read_fun <- function(x) {
    df <- read.csv(x) %>%
    names(df) %<>%
        tolower() %>%
        str_replace_all("_", ".")
    tempdf %<>%
        select(a, b, c, g)
}

Answer 6

截至2020年rename_if，rename_at和rename_all被标记取代。解决这个问题的最新方法 dplyr 方法是rename_with()：

iris %>% rename_with(tolower)

或更复杂的版本：

iris %>% 
  rename_with(stringr::str_replace, 
              pattern = "Length", replacement = "len", 
              matches("Length"))