我正在努力让应用程序第一次做出反应。我使用
创建了我的应用#create df
year <- c(2017, 2017, 2017, 2017, 2017, 2016, 2016, 2016, 2016, 2016)
winner <- c('sam', 'ryan', 'sally', 'sally', 'ryan', 'sally', 'mike', 'ryan', 'mike', 'sam')
loser <- c('mike', 'mike', 'ryan', 'sam', 'sam', 'mike', 'sally', 'mike', 'ryan', 'sally')
df <- data.frame(year, winner, loser)
#successul methods for getting winner's cumulative wins or loser's cumulative losses
df <- as.data.table(df)[, winner_wins := seq(.N), by = "winner"][]
df <- as.data.table(df)[, loser_losses := seq(.N), by = "loser"][]
#successul methods for getting winner's cumulative wins or loser's cumulative losses by year
df <- df %>% group_by(year, winner) %>% mutate(winner_wins = row_number())
df <- df %>% group_by(year, loser) %>% mutate(loser_losses = row_number())
#failed attempt to get winner's cumulative losses by year
df <- df %>% group_by(year) %>% mutate(winner_losses = cumsum(winner == loser & year == year))
一旦我完成了JS方面的工作。我做了：
create-react-native-app applicatin
弹出后。我用XCode打开了iOS版本并构建了＆amp;跑步节目：
react-native eject
模拟器上有红色屏幕：
BUNDLE [ios, dev] ./index.js ░░░░░░░░░░░░░░░░ 0.0% (0/1), failed.
我的应用程序目录中没有index.js或索引相关的文件。 我怎样才能带上index.js？它有什么作用？为什么我错过了这个文件？