将数据框折叠为单行并根据R行创建新列 [英] Collapse data frame into single row and creating new columns based on row R

问题描述

我有一个带有对象名称的数据框，以及该对象的统计时刻列表，如下所示:

I have a data frame with object names and a list of statistical moments for that object, like this:

Object   Mean   IQR   Skew  
   x        1     1      1
   y        2     2      2  
   z        3     3      3

我要为每一行创建带有统计时刻和对象名称前缀的列.像这样:

What i want is to for each row create columns with the statistical moments and the object name prefixed. Like so:

xMean xIQR xSkew yMean yIQR ySkew zMean zIQR zSkew 1 1 1 2 2 2 3 3 3

xMean xIQR xSkew yMean yIQR ySkew zMean zIQR zSkew 1 1 1 2 2 2 3 3 3

从本质上讲，我需要将数据框折叠到一行，这样它就可以在一行上列出所有统计矩，因为我将有很多行，如最后一行，但列的数量有限.

In essence what I need is to collapse a data frame to a single row such that it list all statistical moments on a single line as i'll have many rows like the final one but a finite set of columns.

推荐答案

您可以这样做:

 df1$id <- 1
 reshape(df1, idvar="id", timevar="Object", direction="wide")[-1]
  #  Mean.x IQR.x Skew.x Mean.y IQR.y Skew.y Mean.z IQR.z Skew.z
  #1      1     1      1      2     2      2      3     3      3

或者使用dcast，reshape2中的melt

 library(reshape2)
 dcast(melt(df1, id.var=c('id', 'Object')), id~..., value.var='value')[-1]
 #   x_Mean x_IQR x_Skew y_Mean y_IQR y_Skew z_Mean z_IQR z_Skew
 #1      1     1      1      2     2      2      3     3      3

或使用dplyr和tidyr

 library(dplyr)
 library(tidyr)

  df1 %>% 
      gather(Var, Val, Mean:Skew) %>% 
      unite(VarNew,Object, Var, sep="") %>%
      spread(VarNew, Val) %>%
      select(-id)
  #    xIQR xMean xSkew yIQR yMean ySkew zIQR zMean zSkew
  #1    1     1     1    2     2     2    3     3     3

数据

df1 <- structure(list(Object = c("x", "y", "z"), Mean = 1:3, IQR = 1:3, 
 Skew = 1:3), .Names = c("Object", "Mean", "IQR", "Skew"), class = "data.frame", row.names = c(NA, 
-3L))

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