R中合并的问题

Question

所以我想要以我在下面指出的方式合并一些非常大的数据集。我试着这样做：

setwd(..)
myfiles = list.files(pattern="*.dta")
dflist <- lapply(myfiles, read.dta13)
merged.data.frame = Reduce(function(...) merge(..., all=T), dflist)

但是，我的内存不足...... 还有另一种方法可以在不耗尽内存的情况下实现这一目标吗？

数据框的外观，以及我想要的合并产品：

Dataframe 1
Country   Year Sector          ID  Var 1
Austria   2001 Construction    lp  22 
Austria   2001 Construction    fp  23 
Austria   2001 Manufact        lp  12
Austria   2001 Manufact        fp  43
Austria   2002 Construction    lp  55
Austria   2002 Construction    fp  34
Austria   2002 Manufact        lp  16
Austria   2002 Manufact        fp  76

Dataframe 2
Country   Year Sector         Type  Var1 Var2
Austria   2001 Construction    A    23    5
Austria   2001 Construction    B    34    5
Austria   2001 Manufact        A    98    4
Austria   2001 Manufact        B    48    3
Austria   2002 Construction    A    43    9
Austria   2002 Construction    B    23    7
Austria   2002 Manufact        A    65    6
Austria   2002 Manufact        B    45    6



    Dataframe 3
    Country   Year Sector          Var3 
    Austria   2001 Construction   123      
    Austria   2001 Acco           345
    Austria   2001 Manufact       234    
    Austria   2001 Prod           466
    Austria   2002 Construction   785   
    Austria   2002 Acco           789
    Austria   2002 Manufact       678 
    Austria   2002 Prod           899

Merged:

    Country   Year Sector        ID     Type  Var1 Var2 Var3
    Austria   2001 Construction  lp      NA    22   NA   NA
    Austria   2001 Construction  fp      NA    23   NA   NA
    Austria   2001 Construction  NA      A     23    5   NA
    Austria   2001 Construction  NA      B     34    5   NA
    Austria   2001 Construction  NA      NA    NA   NA   123
    Austria   2001 Manufact      lp      NA    12   NA   NA
    Austria   2001 Manufact      fp      NA    43   NA   NA
    Austria   2001 Manufact      NA      A     98    4   NA
    Austria   2001 Manufact      NA      B     48    3   NA
    Austria   2001 Manufact      NA      NA    NA   NA   234
    Austria   2001 Acco          NA      NA    NA   NA   345
    Austria   2001 Prod          NA      NA    NA   NA   466
    ....      2002 .... 
    and so on.