[R] Help with plotting and date-times for climate data

[Kevin Zembower]

Rui, thanks so much for your clear explanation, solution to my problem,
and additional help with making the graph come out exactly as I was
hoping. I learned a lot from your solution. Thanks, again, for your
help.

-Kevin

On Tue, 2023-09-12 at 23:06 +0100, Rui Barradas wrote:
> Às 21:50 de 12/09/2023, Kevin Zembower via R-help escreveu:
> > Hello,
> > 
> > I'm trying to calculate the mean temperature max from a file of
> > climate
> > date, and plot it over a range of days in the year. I've downloaded
> > the
> > data, and cleaned it up the way I think it should be. However, when
> > I
> > plot it, the geom_smooth line doesn't show up. I think that's
> > because
> > my x axis is characters or factors. Here's what I have so far:
> > ========================================
> > library(tidyverse)
> > 
> > data <- read_csv("Ely_MN_Weather.csv")
> > 
> > start_day = yday(as_date("2023-09-22"))
> > end_day = yday(as_date("2023-10-15"))
> >                 
> > d <- as_tibble(data) %>%
> >      select(DATE,TMAX,TMIN) %>%
> >      mutate(DATE = as_date(DATE),
> >             yday = yday(DATE),
> >             md = sprintf("%02d-%02d", month(DATE), mday(DATE))
> >             ) %>%
> >      filter(yday >= start_day & yday <= end_day) %>%
> >      mutate(md = as.factor(md))
> > 
> > d_sum <- d %>%
> >      group_by(md) %>%
> >      summarize(tmax_mean = mean(TMAX, na.rm=TRUE))
> > 
> > ## Here's the filtered data:
> > dput(d_sum)
> > 
> > > structure(list(md = structure(1:25, levels = c("09-21", "09-22",
> > "09-23", "09-24", "09-25", "09-26", "09-27", "09-28", "09-29",
> > "09-30", "10-01", "10-02", "10-03", "10-04", "10-05", "10-06",
> > "10-07", "10-08", "10-09", "10-10", "10-11", "10-12", "10-13",
> > "10-14", "10-15"), class = "factor"), tmax_mean = c(65,
> > 62.2222222222222,
> > 61.3, 63.8888888888889, 64.3, 60.1111111111111, 62.3, 60.5, 61.9,
> > 61.2, 63.6666666666667, 59.5, 59.5555555555556, 61.5555555555556,
> > 59.4444444444444, 58.7777777777778, 55.8888888888889, 58.125,
> > 58, 55.6666666666667, 57, 55.4444444444444, 49.7777777777778,
> > 48.75, 43.6666666666667)), class = c("tbl_df", "tbl", "data.frame"
> > ), row.names = c(NA, -25L))
> > > 
> > ggplot(data = d_sum, aes(x = md)) +
> >      geom_point(aes(y = tmax_mean, color = "blue")) +
> >      geom_smooth(aes(y = tmax_mean, color = "blue"))
> > =====================================
> > My questions are:
> > 1. Why isn't my geom_smooth plotting? How can I fix it?
> > 2. I don't think I'm handling the month and day combination
> > correctly.
> > Is there a way to encode month and day (but not year) as a date?
> > 3. (Minor point) Why does my graph of tmax_mean come out red when I
> > specify "blue"?
> > 
> > Thanks for any advice or guidance you can offer. I really
> > appreciate
> > the expertise of this group.
> > 
> > -Kevin
> > 
> > ______________________________________________
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> Hello,
> 
> The problem is that the dates are factors, not real dates. And 
> geom_smooth is not interpolating along a discrete axis (the x axis).
> 
> Paste a fake year with md, coerce to date and plot.
> I have simplified the aes() calls and added a date scale in order to 
> make the x axis more readable.
> 
> Without the formula and method arguments, geom_smooth will print a 
> message, they are now made explicit.
> 
> 
> 
> suppressPackageStartupMessages({
>    library(dplyr)
>    library(ggplot2)
> })
> 
> d_sum %>%
>    mutate(md = paste("2023", md, sep = "-"),
>           md = as.Date(md)) %>%
>    ggplot(aes(x = md, y = tmax_mean)) +
>    geom_point(color = "blue") +
>    geom_smooth(
>      formula = y ~ x,
>      method = loess,
>      color = "blue"
>    ) +
>    scale_x_date(date_breaks = "7 days", date_labels = "%m-%d")
> 
> 
> 
> Hope this helps,
> 
> Rui Barradas
>