CODEWITHSUNDEEP
rfunctionplotinterpolation
Til Hund
Til Hund

Reputation: 1681

Interpolation with Gnu R

I have not done this in my life, but is it possible to extract any number of points from a given slope/graph with Gnu R? Do be more precise, can I tell Gnu R to give me 400 points alongside the given data (is it not called interpolation even)? Imagine you have the following data:

dput(df1)
structure(list(census = structure(c(-281037, -253644, -244513, 
-231730, -228077, -217120, -209815, -207989, -191553, -180596, 
-171465, -129462, -98416, -90381, -80154, -71388, -61892, -33768, 
4582, 11887, 15540), class = "Date"), pop_hist = c(0, 30, 1000, 
2000, 3000, 4100, 3900, 4100, 3900, 4000, 4100, 4000, 4030, 4080, 
2000, 1500, 1050, 111, 1936, 3791, 5167)), .Names = c("census", 
"pop_hist"), row.names = c(NA, -21L), class = "data.frame")

and the graphical outputenter image description here

Edit: I have this command from the library(pracma):

interp1(x=as.numeric(census),y=as.numeric(pop_hist),xi=as.numeric(census),method="nearest")

But how can I tell R to give me around 400 points?

Upvotes: 2

Views: 121

Answers (1)

Til Hund
Til Hund

Reputation: 1681

The answer is, thank you wdkrnls:

library(ggplot2)

test <- approx(x=as.numeric(census),y=as.numeric(pop_hist),n=474,method="linear")
ggplot(test,aes(y=y,x=x)) + geom_line()

Upvotes: 1

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