Indicate in which consecutive ages the number of people of the following age is most higher than the-CodePudding

I have a dataframe like this:

Name= letters[1:5]

Amount <- c(1, 4, 9, 2, 0)

df <- data.frame(Name, Amount)

The problem is I have to print a pair of consecutive Name that the Amount of the name after is the most larger than the name previous. For example, in my data frame df:

(a,b) is 1&4 -> 4-1=3

(b,c) is 4&9 -> 9-4=5 (Correct answer)

(c,d) is 9&2 -> 9-2=-7

(d,e) is 2&0 -> 2-0=2

So the answer would be : b c

I have tried something like as.data.frame(table(df)) and count() to extract the desired value but it didn't work.

CodePudding user response：

You want diff and which.max.

with(df, Name[which.max(diff(Amount))   0:1])
#> [1] "b" "c"

CodePudding user response：

If you want a column with the differences you could do something like,

df <- mutate(df, Diff=Amount-lag(Amount)) # get a new column with the difference

Name    Amount  Diff
<chr>   <dbl>   <dbl>
a   1   NA
b   4   3
c   9   5
d   2   -7
e   0   -2