如何使用R將年度數據轉換爲月度數據？

Question

我有從2000年至2015年的15年GDP年度年度數據。我想將這些數據轉換爲月度數據，只有月份和年份。

我只是想將當年的價值複製到所有月份。我如何在R.例如在2010年值是1708，我想爲2010年

我的數據的所有月份複製相同的值：

> str(gdpnew) 
'data.frame': 16 obs. of 3 variables: 
$ X : int 1 2 3 4 5 6 7 8 9 10 ... 
$ Date : Date, format: "2000-12-31" "2001-12-31" "2002-12-31" ... 
$ Value: num 477 494 524 618 722 ... 

> head(gdpnew) 
    X  Date Value 
1 1 2000-12-31 476.636 
2 2 2001-12-31 493.934 
3 3 2002-12-31 523.768 
4 4 2003-12-31 618.369 
5 5 2004-12-31 721.589 
6 6 2005-12-31 834.218 
> 

Answer 1

顯然，你想有一個交叉聯接：

DT <- read.table(text = " X  Date Value 
1 1 2000-12-31 476.636 
2 2 2001-12-31 493.934 
3 3 2002-12-31 523.768 
4 4 2003-12-31 618.369 
5 5 2004-12-31 721.589 
6 6 2005-12-31 834.218", header = TRUE) 

library(data.table) 
setDT(DT) 

DT[, Date := as.IDate(Date)] 
DT[, year := year(Date)] 
setkey(DT, year) 
DT1 <- DT[CJ(year, month = 1:12)] 
print(DT1) 

# X  Date Value year month 
# 1: 1 2000-12-31 476.636 2000  1 
# 2: 1 2000-12-31 476.636 2000  2 
# 3: 1 2000-12-31 476.636 2000  3 
# 4: 1 2000-12-31 476.636 2000  4 
# 5: 1 2000-12-31 476.636 2000  5 
# 6: 1 2000-12-31 476.636 2000  6 
# 7: 1 2000-12-31 476.636 2000  7 
# 8: 1 2000-12-31 476.636 2000  8 
# 9: 1 2000-12-31 476.636 2000  9 
#10: 1 2000-12-31 476.636 2000 10 
#11: 1 2000-12-31 476.636 2000 11 
#12: 1 2000-12-31 476.636 2000 12 
#13: 2 2001-12-31 493.934 2001  1 
#14: 2 2001-12-31 493.934 2001  2 
#15: 2 2001-12-31 493.934 2001  3 
#16: 2 2001-12-31 493.934 2001  4 
#17: 2 2001-12-31 493.934 2001  5 
#18: 2 2001-12-31 493.934 2001  6 
#19: 2 2001-12-31 493.934 2001  7 
#20: 2 2001-12-31 493.934 2001  8 
#21: 2 2001-12-31 493.934 2001  9 
#22: 2 2001-12-31 493.934 2001 10 
#23: 2 2001-12-31 493.934 2001 11 
#24: 2 2001-12-31 493.934 2001 12 
#25: 3 2002-12-31 523.768 2002  1 
#26: 3 2002-12-31 523.768 2002  2 
#27: 3 2002-12-31 523.768 2002  3 
#28: 3 2002-12-31 523.768 2002  4 
#29: 3 2002-12-31 523.768 2002  5 
#30: 3 2002-12-31 523.768 2002  6 
#31: 3 2002-12-31 523.768 2002  7 
#32: 3 2002-12-31 523.768 2002  8 
#33: 3 2002-12-31 523.768 2002  9 
#34: 3 2002-12-31 523.768 2002 10 
#35: 3 2002-12-31 523.768 2002 11 
#36: 3 2002-12-31 523.768 2002 12 
#37: 4 2003-12-31 618.369 2003  1 
#38: 4 2003-12-31 618.369 2003  2 
#39: 4 2003-12-31 618.369 2003  3 
#40: 4 2003-12-31 618.369 2003  4 
#41: 4 2003-12-31 618.369 2003  5 
#42: 4 2003-12-31 618.369 2003  6 
#43: 4 2003-12-31 618.369 2003  7 
#44: 4 2003-12-31 618.369 2003  8 
#45: 4 2003-12-31 618.369 2003  9 
#46: 4 2003-12-31 618.369 2003 10 
#47: 4 2003-12-31 618.369 2003 11 
#48: 4 2003-12-31 618.369 2003 12 
#49: 5 2004-12-31 721.589 2004  1 
#50: 5 2004-12-31 721.589 2004  2 
#51: 5 2004-12-31 721.589 2004  3 
#52: 5 2004-12-31 721.589 2004  4 
#53: 5 2004-12-31 721.589 2004  5 
#54: 5 2004-12-31 721.589 2004  6 
#55: 5 2004-12-31 721.589 2004  7 
#56: 5 2004-12-31 721.589 2004  8 
#57: 5 2004-12-31 721.589 2004  9 
#58: 5 2004-12-31 721.589 2004 10 
#59: 5 2004-12-31 721.589 2004 11 
#60: 5 2004-12-31 721.589 2004 12 
#61: 6 2005-12-31 834.218 2005  1 
#62: 6 2005-12-31 834.218 2005  2 
#63: 6 2005-12-31 834.218 2005  3 
#64: 6 2005-12-31 834.218 2005  4 
#65: 6 2005-12-31 834.218 2005  5 
#66: 6 2005-12-31 834.218 2005  6 
#67: 6 2005-12-31 834.218 2005  7 
#68: 6 2005-12-31 834.218 2005  8 
#69: 6 2005-12-31 834.218 2005  9 
#70: 6 2005-12-31 834.218 2005 10 
#71: 6 2005-12-31 834.218 2005 11 
#72: 6 2005-12-31 834.218 2005 12 
# X  Date Value year month 

你可能需要設置allow.cartesian = TRUE。