Ukázka 2
Data
The atmos data set resides in the nasaweather package of the R programming language. It contains a
collection of atmospheric variables measured between 1995 and 2000 on a grid of 576 coordinates in the
western hemisphere. The data set comes from the 2006 ASA Data Expo.
Some of the variables in the atmos data set are:
• temp - The mean monthly air temperature near the surface of the Earth (measured in kelvins (K))
• pressure - The mean monthly air pressure at the surface of the Earth (measured in millibars (mb))
• ozone - The mean monthly abundance of atmospheric ozone (measured in Dobson units (DU))
You can convert the temperature unit from Kelvin to Celsius with the formula
celsius = kelvins − 273.15
And you can convert the result to Fahrenheit with the formula
fahrenheit = celsius ×
9
5
+ 32
Cleaning
For the remainder of the report, we will look only at data from the year 1995. We aggregate our data by
location, using the R code below.
library(nasaweather)
library(dplyr)
library(ggvis)
year <- 1995
means <- atmos %>%
filter(year == year) %>%
group_by(long, lat) %>%
summarize(temp = mean(temp, na.rm = TRUE),
pressure = mean(pressure, na.rm = TRUE),
ozone = mean(ozone, na.rm = TRUE),
cloudlow = mean(cloudlow, na.rm = TRUE),
cloudmid = mean(cloudmid, na.rm = TRUE),
cloudhigh = mean(cloudhigh, na.rm = TRUE)) %>%
ungroup()
We suspect that group level effects are caused by environmental conditions that vary by locale. To test this
idea, we sort each data point into one of four geographic regions:
means$locale <- "north america"
means$locale[means$lat < 10] <- "south pacific"
means$locale[means$long > -80 & means$lat < 10] <- "south america"
means$locale[means$long > -80 & means$lat > 10] <- "north atlantic"
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lm(ozone ~ temp + locale + temp:locale, data = means)
##
## Call:
## lm(formula = ozone ~ temp + locale + temp:locale, data = means)
##
## Coefficients:
## (Intercept) temp
## 1336.508 -3.559
## localenorth atlantic localesouth america
## 548.248 -1061.452
## localesouth pacific temp:localenorth atlantic
## -549.906 -1.827
## temp:localesouth america temp:localesouth pacific
## 3.496 1.785
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