Untable 已聚合的数据框

Question

我在 R 中有以下数据框：

Name    Year     Apples   Bananas    
Tom     2012        3       4
John    2012        0       1
John    2013        3       2
John    2014        5       3
Alexa   2012        2       2
Alexa   2013        2       1    

我想转换或重塑数据框，以在数据框中表示每个人吃苹果和香蕉的频率。像这样：最好使用 dplyr 或 reshape packages

Name   Year.    Fruit
Tom    2012     Apples
Tom    2012     Apples
Tom    2012     Apples
Tom    2012     Bananas
Tom    2012     Bananas
Tom    2012     Bananas
John   2012     Bananas
John   2013     Apples
John   2013     Apples
John   2013     Apples
John   2013     Bananas
John   2013     Bananas
John   2014     Apples
John   2014     Apples
John   2014     Apples
John   2014     Apples
John   2014     Apples
John   2014     Bananas
John   2014     Bananas
John   2014     Bananas

等等

Answer 1

library( data.table )

#sample data
# mydata <- fread( "Name    Year     Apples   Bananas
# Tom     2012        3       4
# John    2012        0       1
# John    2013        3       2
# John    2014        5       3
# Alexa   2012        2       2
# Alexa   2013        2       1   ")

ans <- melt( setDT( mydata ), id.vars = c("Name","Year"), variable.name = "Fruit" )
ans[ rep(seq(.N), value), !"value"]

输出

#      Name Year   Fruit
#  1:   Tom 2012  Apples
#  2:   Tom 2012  Apples
#  3:   Tom 2012  Apples
#  4:  John 2013  Apples
#  5:  John 2013  Apples
#  6:  John 2013  Apples
#  7:  John 2014  Apples
#  8:  John 2014  Apples
#  9:  John 2014  Apples
# 10:  John 2014  Apples
# 11:  John 2014  Apples
# 12: Alexa 2012  Apples
# 13: Alexa 2012  Apples
# 14: Alexa 2013  Apples
# 15: Alexa 2013  Apples
# 16:   Tom 2012 Bananas
# 17:   Tom 2012 Bananas
# 18:   Tom 2012 Bananas
# 19:   Tom 2012 Bananas
# 20:  John 2012 Bananas
# 21:  John 2013 Bananas
# 22:  John 2013 Bananas
# 23:  John 2014 Bananas
# 24:  John 2014 Bananas
# 25:  John 2014 Bananas
# 26: Alexa 2012 Bananas
# 27: Alexa 2012 Bananas
# 28: Alexa 2013 Bananas
#      Name Year   Fruit