发生这种情况是因为没有唯一标识符，而且spread已被弃用，因此您可以使用pivot_wider。

数据

data <-
tibble::tribble(
      ~Month, ~pH,
   "January", 7.2,
   "January", 5.2,
  "February",   4,
  "February", 7.3,
     "March", 7.1,
     "March",   5
  )

编号

library(dplyr)
library(tidyr)

data %>% 
  group_by(Month) %>% 
  mutate(id = row_number()) %>% 
  pivot_wider(names_from = Month,values_from = pH)

输出

# A tibble: 2 x 4
     id January February March
  <int>   <dbl>    <dbl> <dbl>
1     1     7.2      4     7.1
2     2     5.2      7.3   5