计算变化率

Question

我有一个名为＆＃34; yield＆＃34;的数据集：

diff(yield$count)/yield[-nrow(yield),] * 100

我想确定哪种水果在2008年到2010年间变化率最大。我最接近的是：

fruits

但不仅影响我的year和 private void MyFileSystemWatcher() { _watch = new FileSystemWatcher(path); _watch.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName | NotifyFilters.Size; _watch.Filter = "*.*"; _watch.IncludeSubdirectories = true; _watch.Changed += new FileSystemEventHandler(_watch_Changed); _watch.Created += new FileSystemEventHandler(_watch_Created); _watch.EnableRaisingEvents = true; } private void _watch_Changed(object sender, FileSystemEventArgs e) { Console.WriteLine("File changed: {0}", e.Name); } private void _watch_Created(object sender, FileSystemEventArgs e) { Console.WriteLine("File created: {0}", e.Name); } 列，结果也不正确。

Answer 1

根据您的公式，我认为此dplyr解决方案有效。您需要按水果分组，然后按年份排序，以使lag正常工作：

library(dplyr)
yield %>% 
  group_by(fruits) %>% 
  arrange(fruits, year) %>% 
  mutate(rate = 100 * (count - lag(count))/lag(count)) %>%
  ungroup()

# A tibble: 9 x 4
  fruits   year count   rate
  <fct>   <int> <dbl>  <dbl>
1 apples   2008 10.0    NA  
2 apples   2009 13.0    30.0
3 apples   2010  7.00 - 46.2
4 oranges  2008  5.00   NA  
5 oranges  2009 12.0   140  
6 oranges  2010 14.0    16.7
7 pears    2008 16.0    NA  
8 pears    2009 18.0    12.5
9 pears    2010 20.0    11.1

Answer 2

为了完整性，这里与data.table单行相同。

首先，数据

R> library(data.table)
R> df <- data.frame(fruits=rep(c("apples", "oranges", "pears"), each=3), 
+                   year=rep(2008:2010, 3), 
+                   count=c(10,13,7,5,12,14,16,18,20))
R> dt <- as.data.table(df)
R> dt
    fruits year count
1:  apples 2008    10
2:  apples 2009    13
3:  apples 2010     7
4: oranges 2008     5
5: oranges 2009    12
6: oranges 2010    14
7:   pears 2008    16
8:   pears 2009    18
9:   pears 2010    20
R>

第二，一行

R> dt[ , .(year, change=100*(count-shift(count,1))/shift(count,1)), by=fruits]
    fruits year   change
1:  apples 2008       NA
2:  apples 2009  30.0000
3:  apples 2010 -46.1538
4: oranges 2008       NA
5: oranges 2009 140.0000
6: oranges 2010  16.6667
7:   pears 2008       NA
8:   pears 2009  12.5000
9:   pears 2010  11.1111
R> 

我们将by=fruits分组并在每个块中显示year，并将所需的更改率设置为100*(current-prev)/prev我们使用shift()来延迟 count系列。

Answer 3

R基地一号班轮：

yield$roc <- with(yield, ave(count, fruits, FUN = function(x){c(0, c(diff(x), 0)/x)[1:length(x)]}))

以R为基数，如果您希望NA代替0和实际百分比（即* 100）：

yield$roc <- with(yield, ave(count, fruits, 
              FUN = function(x){c(NA_real_, c(diff(x), 0)/x)[1:length(x)] * 100}))