Warning message:
In mean.default(df) : argument is not numeric or logical: returning NA

目录

Warning message:In mean.default(df) : argument is not numeric or logical: returning NA

问题：

解决：

完整错误：

问题：

字符串是没有办法计算均值的，只有数字才会有这些统计量；

#create data frame
df <- data.frame(team=c('A', 'B', 'C', 'D', 'E'),
                 points=c(99, 90, 86, 88, 95),
                 assists=c(33, 28, 31, 39, 34),
                 rebounds=c(30, 28, 24, 24, 28))

#view data frame
df

#attempt to calculate mean of entire data frame
mean(df)

解决：

#只对单个数值列计算均值

#calculate mean of points column
mean(df$points)

[1] 91.6

#使用sapply方法（只有非数值列会返回NA，其他列正常）

#calculate mean of every column in data frame
sapply(df, mean, 2)

    team   points  assists rebounds 
      NA       90       33       28 

Warning message:
In mean.default(X[[i]], ...) :
  argument is not numeric or logical: returning NA

#使用sapply方法（只有对数值列进行计算均值）

#calculate mean of each numeric column
sapply(df[c('points', 'assists', 'rebounds')], mean, 2)
  points  assists rebounds 
      90       33       28

完整错误：

#attempt to calculate mean of character column
mean(df$team)

Warning message:
In mean.default(df$team) : argument is not numeric or logical: returning NA

#attempt to calculate mean of entire data frame
mean(df)

Warning message:
In mean.default(df) : argument is not numeric or logical: returning NA