如何用NA而不是X制作交叉表? [英] How to make a cross table with NA instead of X?

问题描述

我有以下数据集(请参阅下面的加载数据集)

I have the following dataset (see for loading dataset below)

     ID       Date qty
1  ID25 2007-12-01  45
2  ID25 2008-01-01  26
3  ID25 2008-02-01  46
4  ID25 2008-03-01   0
5  ID25 2008-04-01  78
6  ID25 2008-05-01  65
7  ID25 2008-06-01  32
8  ID99 2008-02-01  99
9  ID99 2008-03-01   0
10 ID99 2008-04-01  99

我想创建一个数据透视表.我使用以下命令来执行此操作，并且似乎运行良好:

And I would like to create a pivot table of that. I do that with the following command and that seems to be working fine:

pivottable <- xtabs(qty ~ ID + Date, table)

输出如下:

ID     2007-12-01 2008-01-01 2008-02-01 2008-03-01 2008-04-01 2008-05-01 2008-06-01
ID25         45         26         46          0         78         65         32
ID99          0          0         99          0         99          0          0

但是，对于ID99，只有3个期间的值，其余部分标记为"0".我想在第一个表中没有任何值的字段中显示NA.我想得到一个如下表:

However, for ID99 there are only values for 3 periods the rest is marked as '0'. I would like to display NA in the fields that have no values in the first table. I would like to get a table that looks as following:

ID     2007-12-01 2008-01-01 2008-02-01 2008-03-01 2008-04-01 2008-05-01 2008-06-01
ID25         45         26         46          0         78         65         32
ID99         NA         NA         99          0         99         NA         NA

关于如何实现此目标的任何建议?

Any suggestion on how to accomplish this?

正在加载数据集:

table <- structure(list(ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 
2L, 2L), .Label = c("ID25", "ID99"), class = "factor"), Date = structure(c(7L, 
1L, 2L, 3L, 4L, 5L, 6L, 2L, 3L, 4L), .Label = c("01/01/2008", 
"01/02/2008", "01/03/2008", "01/04/2008", "01/05/2008", "01/06/2008", 
"01/12/2007"), class = "factor"), qty = c(45L, 26L, 46L, 0L, 
78L, 65L, 32L, 99L, 0L, 99L)), .Names = c("ID", "Date", "qty"
), class = "data.frame", row.names = c(NA, -10L))

table$Date <- as.POSIXct(table$Date, format='%d/%m/%Y')

推荐答案

您可以使用xtabs两次以获取所需的输出:

You could use xtabs twice to obtain the output you are looking for:

1. 创建表:

1. Create the table:

pivottable <- xtabs(qty ~ ID + Date, table)

用NA替换不存在的组合的所有零:

Replace all zeros of non-existing combinations with NA:

pivottable[!xtabs( ~ ID + Date, table)] <- NA

输出:

      Date
ID     2007-12-01 2008-01-01 2008-02-01 2008-03-01 2008-04-01 2008-05-01 2008-06-01
  ID25         45         26         46          0         78         65         32
  ID99                               99          0         99                      

请注意，不会显示NA.这是由于此类的print函数所致.但是您可以使用unclass(pivottable)来实现print的常规行为.

Note that NAs are not displayed. This is due to the print function for this class. But you could use unclass(pivottable) to achieve regular behavior of print.

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