如何用子串替換多個列名稱

Question

我想用substring（）編輯多個列名稱。只有我寫的代碼不起作用。

奇怪的是下面的代碼有效。 舊列名：

oldColNames <- names(forcesdf[,c(5:20)]) 

結果：

> names(forcesdf[,c(5:20)]) 
[1] "2000 [YR2000]" "2001 [YR2001]" "2002 [YR2002]" "2003 [YR2003]" "2004 [YR2004]" "2005 [YR2005]" "2006 [YR2006]" 
[8] "2007 [YR2007]" "2008 [YR2008]" "2009 [YR2009]" "2010 [YR2010]" "2011 [YR2011]" "2012 [YR2012]" "2013 [YR2013]" 
[15] "2014 [YR2014]" "2015 [YR2015]" 

而新的列名：

newColNames <- substring(names(forcesdf[,c(5:20)]), 1, 4) 
oldColNames <- newColNames 

結果我excually想：

> oldColNames 
[1] "2000" "2001" "2002" "2003" "2004" "2005" "2006" "2007" "2008" "2009" "2010" "2011" "2012" "2013" "2014" "2015" 

中當然，我想改變我的數據框中的列名，所以最初，我寫了下面的代碼，但名稱沒有改變。

names(forcesdf[,c(5:20)]) <- substring(names(forcesdf[,c(5:20)]), 1, 4) 

> names(forcesdf[,c(5:20)]) 
[1] "2000 [YR2000]" "2001 [YR2001]" "2002 [YR2002]" "2003 [YR2003]" "2004 [YR2004]" "2005 [YR2005]" "2006 [YR2006]" 
[8] "2007 [YR2007]" "2008 [YR2008]" "2009 [YR2009]" "2010 [YR2010]" "2011 [YR2011]" "2012 [YR2012]" "2013 [YR2013]" 
[15] "2014 [YR2014]" "2015 [YR2015]" 

Answer 1

測試此

names(forcesdf)[5:20] <- substring(names(forcesdf[,c(5:20)]), 1, 4) 

Answer 2

如果你這樣做你可以改變他們：

names(forcesdf)[5:20] <- substring(names(forcesdf)[5:20], 1, 4) 

我覺得關鍵是在你的代碼進行子集列名，但不能引用到他們。