Hello, I'd like to know how to calculate the price change from one period to the next. Example:
Year | Price
2007 | 25
2008 | 30
2009 | 7
2010 | 15
... | ... | ...
The new column would look like:
Year | Contact Us | Variation
2007 | 25 | 25-0 = 25
2008 | 30 | 30-25 = 5
2009 | 7 | 7-30 = -23
2010 | 15 | 15-7 = 8
... | ... | ... | ...
I have no idea how to do this. Thank you in advance!
You can use the diff() function:
#dados
df <- data.frame(Ano = c(2007,2008,2009,2010), Preço = c(25,30,7,15))
diff(df$Preço)
# [1] 5 -23 8
The diff() function ignores the first element. To get the result of your example, we can use the append() function to add the first element:
df$Variação <- append(df$Preço[1], diff(df$Preço))
df
# Ano Preço Variação
# 1 2007 25 25
# 2 2008 30 5
# 3 2009 7 -23
# 4 2010 15 8