R help - May 2023 - Newbie: Drawing fitted lines on subset of data

Hello,

I's still working with my tsibble of weight data for the last 20 years. 
In addition to drawing an overall trend line, using lm, for the whole 
data set, I'd like to draw short lines that would recompute lm and draw 
it, say, just for the years from 2010:2015.

Here's a short example that I think illustrates what I'm trying to do. 
The commented out sections show what I've tried to far:

## Short example to test segments:

w <- tsibble(
     date = as.Date("2022-01-01") + 0:99,
     value = rnorm(100)
)

ggplot(data = w, mapping = aes(date, value)) +
     geom_smooth(method = "lm", se = FALSE) +
     geom_point()
     ## Below gives error about ignoring data
     ## geom_abline( data = w$date[25:75] )
     ## Gives error ''data' must be in <data.frame>'
     ## geom_smooth(data = w$date[25:35],
     ##             method = lm,
     ##             color = "black",
     ##             se = FALSE)

I'm thinking that this is probably easily done, but I'm struggling with 
how to subset the data in the middle of the pipeline.

Thanks for any advice and help.

-Kevin

?s 15:29 de 16/05/2023, Kevin Zembower via R-help
escreveu:
> Hello,
> 
> I's still working with my tsibble of weight data for the last 20 years.
> In addition to drawing an overall trend line, using lm, for the whole
> data set, I'd like to draw short lines that would recompute lm and draw
> it, say, just for the years from 2010:2015.
> 
> Here's a short example that I think illustrates what I'm trying to
do.
> The commented out sections show what I've tried to far:
> 
> ## Short example to test segments:
> 
> w <- tsibble(
>       date = as.Date("2022-01-01") + 0:99,
>       value = rnorm(100)
> )
> 
> ggplot(data = w, mapping = aes(date, value)) +
>       geom_smooth(method = "lm", se = FALSE) +
>       geom_point()
>       ## Below gives error about ignoring data
>       ## geom_abline( data = w$date[25:75] )
>       ## Gives error ''data' must be in <data.frame>'
>       ## geom_smooth(data = w$date[25:35],
>       ##             method = lm,
>       ##             color = "black",
>       ##             se = FALSE)
> 
> I'm thinking that this is probably easily done, but I'm struggling
with
> how to subset the data in the middle of the pipeline.
> 
> Thanks for any advice and help.
> 
> -Kevin
> 
> ______________________________________________
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Hello,

Try the following.
In the 2nd geom_smooth you need a subset of the data not of just one of 
its columns.



suppressPackageStartupMessages({
   library(tsibble)
   library(dplyr)
   library(ggplot2)
   library(lubridate)
})

ggplot(data = w, mapping = aes(date, value)) +
   geom_smooth(formula = y ~ x, method = "lm", se = FALSE) +
   geom_point() +
   geom_smooth(
     data = w %>% filter(year(date) >= 2010, year(date) <= 2015),
     mapping = aes(date, value),
     formula = y ~ x,
     method = lm,
     color = "black",
     se = FALSE
   )


Other ways to subset the data are


# dplyr
data = w %>% filter(year(date) %in% 2010:2015)
# base R
data = subset(w, year(date) %in% 2010:2015)


Hope this helps,

Rui Barradas