展开数据框 [英] Expand Data Frame
问题描述
我想在某些条件下扩展数据框.它有点类似于这个问题expand data frames inside data frame,但是不太一样.
I want to expand a data frame given some conditions. It is a bit similar to this question expand data frames inside data frame, but not quite the same.
我有一个数据框:
df = data.frame(ID = c(3,3,3,3, 17,17,17, 74, 74, 210, 210, 210, 210), amount = c(101, 135, 101, 68, 196, 65 ,135, 76, 136, 15, 15, 15 ,15), week.number = c(4, 6, 8, 10, 2, 5, 7, 2, 6, 2, 3, 5, 6))
我想扩展每个 ID 的数据框,给定最小和最大周数,并且在此扩展的金额列中为 0.最小周数为 1,最大周数为 10.预期结果为:
I want to expand the data frame for each ID, given a min and max week.number, and having 0 in the amount column for this expansion. Min week.number is 1 and max week.number is 10. The expected results would be:
df1 <- data.frame(ID = c(rep(3,10), rep(17, 10), rep(74, 10), rep(210, 10)),
amount = c(0, 0, 0, 101, 0, 135, 0, 101, 0, 68, 0, 196,
0, 0, 65, 0, 135, 0, 0, 0, 0, 76, 0, 0, 0,
136, 0, 0, 0, 0, 0, 15, 15, 0, 15, 15, 0, 0,
0, 0))
(实际上,我有数千个 ID,周数从 1 到 160).
(In reality, I have thousands of ID and week number goes from 1 to 160).
有没有简单快捷的方法来做到这一点?
Is there a simple, fast way to do this?
谢谢!
推荐答案
With data.table
(tx to Frank 修正结果的长度):
With data.table
(tx to Frank for correcting the length of the result):
require(data.table)
dt<-as.data.table(df)
f<-function(x,y,len=max(y)) {res<-numeric(len);res[y]<-x;res}
dt[,list(amount=f(amount,weeek.number,10)),by=ID]
# ID amount
# 1: 3 0
# 2: 3 0
# 3: 3 0
# 4: 3 101
# 5: 3 0
# 6: 3 135
# 7: 3 0
# 8: 3 101
# 9: 3 0
#10: 3 68
# ......
编辑
我刚刚注意到你的 amount
和 weeek.number
实际上定义了一个 sparseVector
,即一个主要由零组成的向量,其中只有索引的非零元素被保留.因此,您可以尝试使用 Matrix
包:
I just noticed that your amount
and weeek.number
actually define a sparseVector
, i.e. a vector made mainly of zeroes where just the indices of the non-zero elements is kept. So, you can try with the Matrix
package:
require(Matrix)
dt[,list(as.vector(sparseVector(amount,weeek.number,10))),by=ID]
得到与上面相同的结果.
to get the same result as above.
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