R Plyr写入CSV

Question

我正在尝试拆分一个数据帧，并使用一个变量中的唯一值将其写入r中的csv文件。我是r的新手，我不能完全确定我知道自己在做什么。

 ## trying to subset data
    library(dplyr)
    library(plyr)
    #set the working directory
    setwd("S:/some stuff")

    ## load the datafile into an object called data. 
    data <- read.csv("S:/some stuff/Area.csv",
                       header = TRUE, sep = ",")
#Create subsets of data by LA
LA<-subset(data,AREA == "LA")

我的数据框有2,500个观察值和20个变量。

我的数据帧被称为LA，我想将其拆分的变量称为疾病

我找到了这个How to create multiple ,csv files in R?

并相应地对其进行重新分配

从…

plyr::d_ply(iris, .(Species), function(x) write.csv(x, 
  file = paste(x$Species, ".csv", sep = "")))

至

plyr::d_ply(LA, .(Disease), function(x) write.csv(x,
file = paste(LA$Disease, ".csv", )))

然而……

Error in file(file, ifelse(append, "a", "w")) : 
  invalid 'description' argument
In addition: Warning message:
In if (file == "") file <- stdout() else if (is.character(file)) { :

 Show Traceback

 Rerun with Debug
 Error in file(file, ifelse(append, "a", "w")) : 
  invalid 'description' argument 

有两件事我想解决。1)子集数据帧2)写入路径

理想情况下，我希望在导入数据( Area.csv文件)时遍历它。这是有区域和疾病的。有12个地区，20种疾病。我想按区域创建每个疾病的csv文件。在本例中，面积= LA，然后是疾病。

如何使用循环为每个区域创建20个不同的文件？

我是这样想的：https://blog.ouseful.info/2013/04/03/splitting-a-large-csv-file-into-separate-smaller-files-based-on-values-within-a-specific-column/

    mpExpenses2012 = read.csv("~/Downloads/DataDownload_2012.csv")
#mpExpenses2012 is the large dataframe containing data for each MP
#Get the list of unique MP names
for (name in levels(mpExpenses2012$MP.s.Name)){
  #Subset the data by MP
  tmp=subset(mpExpenses2012,MP.s.Name==name)
  #Create a new filename for each MP - the folder 'mpExpenses2012' should already exist
  fn=paste('mpExpenses2012/',gsub(' ','',name),sep='')
  #Save the CSV file containing separate expenses data for each MP
  write.csv(tmp,fn,row.names=FALSE)
}

可能会有帮助，但它写的是一条让我沮丧的道路。

编辑

library(tidyr)
library(purrr)
temp_dir <- tempfile()
dir.create(temp_dir)

LA %>%
  nest(-FinalDiseaseForMonthlyAnalysis) %>% 
  pwalk(function(FinalDiseaseForMonthlyAnalysis, data) write.csv(data, file.path(temp_dir, paste0(FinalDiseaseForMonthlyAnalysis, ".csv"))))
list.files(temp_dir)
temp_dir
unlink(temp_dir, recursive = T)

这是可行的。但是现在出现了“文件在哪里？”有个问题。是:我得到临时文件，然后解除链接。但是如何保存在S:/some stuff/上的文件夹中呢？

编辑最终:解决了我读到r中的所有东西都是一个列表的问题。我找到了一种方法，将其分成两列来做我需要的事情。令人恼火的是，它链接在这里的评论中：https://blog.ouseful.info/2013/04/03/splitting-a-large-csv-file-into-separate-smaller-files-based-on-values-within-a-specific-column/

我错过了。我在使用dir.create生成目录时也遇到了问题。谁知道当你尝试做一些事情时，dir.create需要有recursive = TRUE呢？我现在知道了。

不管怎么说。下面是我所做的：

## trying to subset data
# generate data:
library(tidyr)
    library(purrr)
    library(dplyr)
    library(write)
 ## set working directory
    setwd("S:/somestuff")

    #create the directories - pretty sure there's a way to avoid doing this long hand
    dir.create("S:/somestuff/CSV source files", recursive = TRUE)
    dir.create("S:/somestuff/CSV source files/LA1", recursive = TRUE)
    dir.create("S:/somestuff/CSV source files/LA2", recursive = TRUE)
    dir.create("S:/somestuff/CSV source files/LA3", recursive = TRUE)


    #Read in the CSV
    DF = read.csv("S:/somestuff/CSV source files/ALL.csv",
                       header = TRUE, sep = ",")
    glimpse(DF) 

    #This splits the dataframe generated above (DF) and calls it DF4
    DF4 <- split(DF,list(DF$LA,DF$FinalDiseaseForMonthlyAnalysis))
    lapply(names(DF4), function(name) write.csv(DF4[[name]], file = paste("S:/somestuff/CSV source files/",gsub('','',name),sep = ''), row.names = F))

我猜如果我读入数据帧，我就可以使用dir.create从数据帧中LA中的名称创建路径。

回到问题之后。在最新版本的dplyr中，这要容易得多

ourdata<-DF4%>%
  group_by(DF$LA,DF$FinalDiseaseForMonthlyAnalysis)%>%
  group_walk(~ write_csv(.x, paste0(.y$LA,.y$FinalDiseaseForMonthlyAnalysis, ".csv")))

Answer 1

最后，我使用了：

## trying to subset data
# generate data:
library(tidyr)
library(purrr)
library(dplyr)
library(stringr)
library(plyr)
library (car)
## set working directory
setwd("S:/Somestuff/Borough profile maps/Working")

## read data in from geocoded file
geocoded<-read.csv("geocoded 2015 - 2018.csv",na.strings=c(""," ","N/A"))

str(geocoded)
str(geocoded$GENDER)
levels(geocoded$LA)

#split geocoded data by LA 
x <-split(geocoded,geocoded$LA)
str(x)

#Split geocoded data by LA and Final
#split(x, f, drop = FALSE, sep = ".", lex.order = FALSE, .)
y<-split(geocoded,list(geocoded$Final,geocoded$LA), drop = TRUE, sep = "_")
str(y)

#create dir and then write CSV files of geocoded to file locations
dir.create("S:/Somestuff/Borough profile maps/Working/TEST/",, recursive = TRUE)
dir.create("S:/Somestuff/Borough profile maps/Working/TEST/TEST2",, recursive = TRUE)
lapply(names(x), function(name) write.csv(x[[name]], file = paste('S:/Somestuff/Borough profile maps/Working/TEST/',gsub(' ','',name),sep = ''), row.names = F))
lapply(names(y),function(name) write.csv(y[[name]], file = paste('S:/Somestuff/Borough profile maps/Working/TEST/TEST2/',name,".csv")))

问题在于，在我的原始代码中，您会注意到我使用的是read.csv，但输入的是一个.txt文件。我将文件更改为.csv和BANG。啊，真灵。第一次。

我意识到你并不需要我在开始时调用的所有库，但在我荒谬的尝试次数中，它们被留在了那里。

Answer 2

回到问题之后。在最新版本的dplyr中，这要容易得多

DF4%>%
      group_by(DF$LA,DF$FinalDiseaseForMonthlyAnalysis)%>%
      group_walk(~ write_csv(.x, paste0(.y$LA,.y$FinalDiseaseForMonthlyAnalysis, ".csv")))