旧行李 2012-05-21 16:35 采纳率: 25%
浏览 5487
已采纳

创建一个空 data.frame

I'm trying to initialize a data.frame without any rows. Basically, I want to specify the data types for each column and name them, but not have any rows created as a result.

The best I've been able to do so far is something like:

df <- data.frame(Date=as.Date("01/01/2000", format="%m/%d/%Y"), 
                 File="", User="", stringsAsFactors=FALSE)
df <- df[-1,]

Which creates a data.frame with a single row containing all of the data types and column names I wanted, but also creates a useless row which then needs to be removed.

Is there a better way to do this?

转载于:https://stackoverflow.com/questions/10689055/create-an-empty-data-frame

  • 写回答

14条回答 默认 最新

  • ℙℕℤℝ 2012-05-21 16:44
    关注

    Just initialize it with empty vectors:

    df <- data.frame(Date=as.Date(character()),
                     File=character(), 
                     User=character(), 
                     stringsAsFactors=FALSE) 
    

    Here's an other example with different column types :

    df <- data.frame(Doubles=double(),
                     Ints=integer(),
                     Factors=factor(),
                     Logicals=logical(),
                     Characters=character(),
                     stringsAsFactors=FALSE)
    
    str(df)
    > str(df)
    'data.frame':   0 obs. of  5 variables:
     $ Doubles   : num 
     $ Ints      : int 
     $ Factors   : Factor w/ 0 levels: 
     $ Logicals  : logi 
     $ Characters: chr 
    

    N.B. :

    Initializing a data.frame with an empty column of the wrong type does not prevent further additions of rows having columns of different types.
    This method is just a bit safer in the sense that you'll have the correct column types from the beginning, hence if your code relies on some column type checking, it will work even with a data.frame with zero rows.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(13条)

报告相同问题?

悬赏问题

  • ¥15 求差集那个函数有问题,有无佬可以解决
  • ¥15 【提问】基于Invest的水源涵养
  • ¥20 微信网友居然可以通过vx号找到我绑的手机号
  • ¥15 寻一个支付宝扫码远程授权登录的软件助手app
  • ¥15 解riccati方程组
  • ¥15 display:none;样式在嵌套结构中的已设置了display样式的元素上不起作用?
  • ¥15 使用rabbitMQ 消息队列作为url源进行多线程爬取时,总有几个url没有处理的问题。
  • ¥15 Ubuntu在安装序列比对软件STAR时出现报错如何解决
  • ¥50 树莓派安卓APK系统签名
  • ¥65 汇编语言除法溢出问题