r - 日期差异直方图 - 分组

Question

前几天我问了一个关于如何获得日期差异直方图的问题。我想做同样的事情，但对于组和箱线图，使用格子的 bwplot。本质上，对于我拥有的 5 个不同来源中的每一个，都需要 1 个带有 5 个方框图的图像(我在下面的示例中显示了 2 个)——类似这样的 .

我花了很长时间试图弄清楚这一点，但无法得到它。

我能想到的最接近的

df <- read.csv("~/dates.csv", header = TRUE, sep = ",", quote = "\"")
a <- aggregate(as.POSIXct(as.character(df$REQUEST_DATE), format="%m/%d/%Y %H:%M:%S"), list(SOURCE=df$SOURCE), diff) # not sure if this is right (and I need -diff, but can't do that)
# now what?  I seem to know how to access a$SOURCE, but don't know how to look at the data associated with a$SOURCE.

数据(~/dates.csv):

"SOURCE","REQUEST_DATE"
"A","09/11/2011 09:28:48"
"A","09/11/2011 09:21:15"
"A","09/11/2011 09:15:42"
"A","09/11/2011 09:12:18"
"D","09/13/2011 09:06:53"
"D","09/13/2011 09:06:18"
"D","09/13/2011 08:56:55"
"D","09/13/2011 08:56:18"
"D","09/13/2011 08:55:43"
"D","09/13/2011 08:39:07"

Answer 1

这是使用 plyr 的解决方案数据分析包，以及 ggplot2情节包:

读取数据。注意使用 stringsAsFactors=FALSE - 这样可以省去很多转换为 as.character 的麻烦之后:

df <- read.csv(textConnection('
"SOURCE","REQUEST_DATE"
"A","09/11/2011 09:28:48"
"A","09/11/2011 09:21:15"
"A","09/11/2011 09:15:42"
"A","09/11/2011 09:12:18"
"D","09/13/2011 09:06:53"
"D","09/13/2011 09:06:18"
"D","09/13/2011 08:56:55"
"D","09/13/2011 08:56:18"
"D","09/13/2011 08:55:43"
"D","09/13/2011 08:39:07"
'), stringsAsFactors=FALSE)

转换为 POSIX 日期格式:

df$REQUEST_DATE <- as.POSIXct(df$REQUEST_DATE, format="%m/%d/%Y %H:%M:%S")

负载 plyr并使用 ddply a) 按 SOURCE 分组，b) 计算 difftime，c) 将结果分组到一个 data.frame 中，只需一步:

library(plyr)
df_diff <- ddply(df, .(SOURCE), summarize, TIME_DIFF=-unclass(diff(REQUEST_DATE)))
df_diff
  SOURCE TIME_DIFF
1      A      7.55
2      A      5.55
3      A      3.40
4      D     35.00
5      D    563.00
6      D     37.00
7      D     35.00
8      D    996.00

负载 ggplot2和情节。该图看起来有点垃圾 - 那是因为样本数据集很小。它将在更大的数据集上更好地工作，即您将在中值、范围和异常值之间得到清晰的分离。

library(ggplot2)
ggplot(df_diff, aes(y=TIME_DIFF, x=SOURCE)) + geom_boxplot()