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我有一个关于导入多个数据（excel或csv）的问题。
我知道如果我想同时读取多个excel数据（相同的列名），代码是： 

library(readxl)
file.list <- dir(path = "/path", pattern='\\.xlsx', full.names = T)
df.list <- lapply(file.list, read_excel)
data <- rbindlist(df.list)

因此，我同时阅读它们并合并为一个数据。
但是，我以我的一个数据为例。
在 excel 中，row1有一个标题名称，而row2是header，所以obs.从row3开始。此外，如果EXCEL
中的第一个数据如下所示：

TITLE~~~~~
col1    col2    col3
A       1       3.59283E+14 
B       2       3.59258E+14
C       3       3.59286E+14
REFUND
A       -1      3.59286E+14

但是，col3在excel中被定义为数字。实际上，它看起来像： 

TITLE~~~~~
col1    col2    col3
A       1       359283060959987 
B       2       359258069826064
C       3       359286062903911
REFUND
A       -1      359283060959987

第 6 行有REFUND. 在我的多个数据中，我不知道哪一行有REFUND. 我想读我的obs。没有这些行。我能怎么做？
其实col3是character。但在 excel 中，它看起来像numeric.
我如何将它定义为character导入到 R 时，所以导入后，它不显示指数符号。

4

1 回答 1

1

我认为没有 REFUND 行，至少有read_excel函数可以直接读取数据。但是我在 R 中很新，我可能是错的。

也就是说，我首先想到的是构建自己的功能。下面的一个似乎工作。

library(readxl)
library(data.table)

file.list <- dir(path = ".", pattern='\\.xlsx', full.names = T)

my_read_data<-function(x){ #x list of files

  df.list<- lapply(x, function(x){read_excel(path=x,skip=1,col_names = TRUE,
                                             col_types=c("text","numeric","text"))})
  #skip -> skip the line with the title
  #col_names -> use the first row as column names, i.e., col1, col2 and col3
  #col_types-> vector containing one entry per column indicating the type of data

  my.data <- rbindlist(df.list)
  my.data.clean<-my.data[my.data$col1!="REFUND",]  #select only rows without "REFUND"

  return(my.data.clean)
}

为了运行该功能，我将您的 Excel 示例复制了四次，更改了 REFUND 行的位置。我得到的结果如下。

the.data<-my_read_data(file.list) 

>the.data
   col1 col2            col3
1:    A    1 359283060959987
2:    B    2 359258069826064
3:    C    3 359286062903911
4:    A   -1 359283060959987
5:    A    1 359283060959987
6:    B    2 359258069826064
7:    C    3 359286062903911
8:    A   -1 359283060959987
9:    A    1 359283060959987
10:    B    2 359258069826064
11:    C    3 359286062903911
12:    A   -1 359283060959987
13:    A    1 359283060959987
14:    B    2 359258069826064
15:    C    3 359286062903911
16:    A   -1 359283060959987

EDIT - 传递要更改为字符类型的列的函数

关于您的评论，也许您可​​以考虑使用此功能：

my_read_data2<-function(x,character_col=NULL){ #x->list of files 
                                               # character_col->column to be change to character
                                              # can be more than one

  df.list<- lapply(x, function(x){read_excel(path=x,skip=1,col_names = TRUE)})
  my.data <- rbindlist(df.list)
  my.data.clean<-my.data[my.data$col1!="REFUND",]  #select only rows without "REFUND"

  # changing column selected by character_col to character
  # since the result from step above is a data table, 
  # access to elements is different from data frame

  if(!is.null(character_col)){ #this allow you to use the function using only
                               # default results from read_excel

      my.data.clean[, eval(character_col):= lapply(.SD, as.character),
                    .SDcols= character_col]
  }
  # eval -> you need to evaluate the argument you pass to the function,
  #         otherwise you'll end up with an additional character_col column
  #         that will be a list of all the columns you include in .SDcols
  #.SD -> is the subset of the data table, in this case 
  #       .SDcols specifies the columns that are included in .SD.

  return(my.data.clean[]) # in that case, don't forget the [] to avoid
                          #the odd behaviour when calling your resulting data table
                          #(see link at the end)                            
 }

例子：

    the.data<-my_read_data2(file.list)
str(the.data)

 >str(the.data)
    Classes ‘data.table’ and 'data.frame':  16 obs. of  3 variables:
    $ col1: chr  "A" "B" "C" "A" ...
    $ col2: num  1 2 3 -1 1 2 3 -1 1 2 ...
    $ col3: num  3.59e+14 3.59e+14 3.59e+14 3.59e+14 3.59e+14 ...
    - attr(*, ".internal.selfref")=<externalptr> 

the.data1<-my_read_data2(file.list,"col3")
str(the.data1) 

> str(the.data1)
    Classes ‘data.table’ and 'data.frame':  16 obs. of  3 variables:
    $ col1: chr  "A" "B" "C" "A" ...
    $ col2: num  1 2 3 -1 1 2 3 -1 1 2 ...
    $ col3: chr  "359283060959987" "359258069826064" "359286062903911" "359283060959987" ...
    - attr(*, ".internal.selfref")=<externalptr>

您还可以使用多个列：

the.data2<-my_read_data2(file.list,c("col2","col3"))
the.data3<-my_read_data2(file.list,c(2,3))

从函数返回后未打印 data.table 对象

希望对你有帮助

于 2017-05-15T08:15:52.367 回答