2
下面是一個示例數據集和一些令我困擾的代碼行。我無法弄清楚如何將這些派生變量(Year和Session)轉換爲數字,以便我可以得到適當的摘要並使用「子集」函數。將類和模式從字符更改爲數字
##Generate sample dataset
df=data.frame(StudyAreaVisitNote=c("2006 Session 1","2006 Session 2", "2008 Session 4", "2012 Session 3"))
##Create new column denoting year and session on their own
as.factor(df$StudyAreaVisitNote)
df$Year <- substr(x = df$StudyAreaVisitNote, start = 1, stop = 4)
df$Session <- substr(x = df$StudyAreaVisitNote, start = 13, stop = 14)
##Summary of Data
summary(df) ## Year and Session are Class and Mode "Character", summary provides little info
##Turn Year and Session into Numeric
as.numeric(df$Year)
as.numeric(df$Session)
##Try Summary of Data Again
summary(df) ## Again, Year and Session are Class and Mode "Character", summary provides little info
你需要重新分配你想改變,即'$ DF年<列 - as.numeric(DF $年)',類似的還有'Session' – 2014-09-13 19:42:38
哦天哪,葉氏工作完美,謝謝! – ctlamb 2014-09-13 19:44:27