[R] Help with plotting and date-times for climate data
Rui Barradas
ru|pb@rr@d@@ @end|ng |rom @@po@pt
Wed Sep 13 00:06:43 CEST 2023
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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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
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