group_by(Country.Region) 中的错误：找不到对象“Country.Region”

Question

我正在尝试为冠状病毒创建一个闪亮的应用程序。

library(data.table)
library(magrittr)
library(dplyr)

url <- "https://github.com/datasets/covid-19/blob/master/time-series-19-covid-combined.csv"

data <- read.csv(url)

Confirmed <- data[which(data$Date=="2020-03-12"),] %>%
  group_by(Country.Region) %>%
  summarise(Confirmed = sum(Confirmed)) %>%
  arrange(desc(Confirmed))

在Confirmed，我收到一个错误：

group_by(Country.Region) 中的错误：找不到对象“Country.Region”

Answer 1

试试这个：

URL <- "https://raw.githubusercontent.com/datasets/covid-19/master/time-series-19-covid-combined.csv"

data <- read.csv(url(URL), stringsAsFactors = FALSE)  # important !
str(data)  # Always check before continuing further

---

'data.frame':   12768 obs. of  8 variables:
 $ Province.State: Factor w/ 164 levels "","Alameda County, CA",..: 4 4 4 4 4 4 4 4 4 4 ...
 $ Country.Region: Factor w/ 111 levels "Afghanistan",..: 60 60 60 60 60 60 60 60 60 60 ...
 $ Lat           : num  31.8 31.8 31.8 31.8 31.8 ...
 $ Long          : num  117 117 117 117 117 ...
 $ Date          : chr  "2020-01-22" "2020-01-23" "2020-01-24" "2020-01-25" ...
 $ Confirmed     : int  1 9 15 39 60 70 106 152 200 237 ...
 $ Recovered     : int  0 0 0 0 0 0 0 2 2 3 ...
 $ Deaths        : int  0 0 0 0 0 0 0 0 0 0 ...

请注意，“日期”是字符。您需要将其转换为“日期”类

library(dplyr)
data <- data %>%
  mutate(Date = as.Date(Date))

Confirmed <- data %>%
  filter(Date=="2020-03-12") %>%
  group_by(Country.Region) %>%
  summarise(Confirmed = sum(Confirmed)) %>%
  arrange(desc(Confirmed))

# A tibble: 0 x 2
# ... with 2 variables: Country.Region <chr>, Confirmed <int>