R - 计算不同时间间隔之间的运行总计

Question

我有一个跟踪一些贷款余额的数据框。每次向余额（“金额”）付款时，该物业贷款的新余额都会显示在“余额”列中。

df = data.frame(Date = c("2015-03-01", "2015-05-01", "2016-07-02", "2017-11-24", "2017-12-15"),
            Property = c("1 Main St", "1 Main St", "1 Main St", "5 Main St", "1 Main St"),
            Amount = c(50000, -10000, -5000, 75000, -4000),
            Balance = c(50000, 40000, 35000, 75000, 31000)
            )

如您所见，日期相当分散，大多数月份没有任何交易记录。我希望能够在每个月初制作一个包含每个属性余额的数据框，无论当月是否有交易。像这样的：

Month = c("March 2015", "April 2015", "May 2015", "June 2015"),
Property = c("1 Main St", "1 Main St", "1 Main St", "1 Main St").
Balance = c(50000, 50000, 40000, 40000)

它还需要能够处理当月的最后一笔交易（如果在给定的月份内有多个房产交易）。任何想法如何处理这个？

Answer 1

首先，确保您的Date 字段的类型为“日期”。这是我用来处理你的数据的调用：

df = data.frame(Date = as.Date(c("2015-03-01", "2015-05-01", "2016-07-02", "2017-11-24", "2017-12-15"), "%Y-%m-%d"),
            Property = c("1 Main St", "1 Main St", "1 Main St", "5 Main St", "1 Main St"),
            Amount = c(50000, -10000, -5000, 75000, -4000),
            Balance = c(50000, 40000, 35000, 75000, 31000),
            stringsAsFactors = FALSE
            )

注意，我还在 data.frame 调用中添加了 stringsAsFactors = FALSE 参数。

然后，我使用以下代码也许（？）回答了您的问题：

library(tidyr)
library(dplyr)
library(lubridate)

arrange(df, Date)

from <- first(df$Date)
to <- last(df$Date)

new_df <- df %>%
        complete(Date = seq.Date(from, to, "day"))%>%
        fill(Property:Balance)%>%
        group_by(year = year(Date), month=month(Date, label = TRUE), Property)%>%
        summarise(Balance = last(Balance))