将一列传播到 R 中的多列（传播？，重塑？）

Question

我想删除下表中的 Station.ID 列，方法是将其分配（Spread？，Reshape？）到月份列，以便获得 Jan_323、Feb_323、...、Jan_452、Feb_452 等列, ...

 Have:

 Station.ID  Year    Jan   Feb    Mar   Apr  May   Jun
 323         1995    31.3  25.2   19.0   15.0 ..    .. 
 323         1996    28.0  20.2   17.5   14.0 ..    ..
 323         ...     ..    ..     ..     ..   ..    ..
 ...         ...     ..    ..     ..     ..   ..    ..
 452         1995    16.2  ..     ..     ..   ..    ..
 452         1996    14.3  ..     ..     ..   ..    ..
 452         ...     ..    ..     ..     ..   ..    ..
 ..          ...     ..    ..     ..     ..

 Want:

 Year    Jan_323  Feb_323   Mar_323  ...  Jan_452   Feb_452   Mar_452   ...
 1995     31.3     25.2     19.0     ...   16.2       ...       ...     ...
 1996     28.0      ...       ...    ...   14.3       ...       ...     ...
 1997     ...       ...       ...    ...   ...        ...       ...     ...    
 1998     ...       ...       ...    ...   ...        ...       ...     ...
 ....     ...       ...       ...    ...   ...        ...       ...     ...

Answer 1

我们可以在gathering 后使用spread 转换为“长”格式

library(tidyverse)
gather(df1, key, value, -Station.ID, -Year) %>% 
      unite(Station.ID, key, Station.ID) %>% 
      mutate(Station.ID = factor(Station.ID, levels = unique(Station.ID))) %>%
      spread(Station.ID, value)
#   Year Jan_323 Jan_452 Feb_323 Feb_452 Mar_323 Mar_452 Apr_323 Apr_452 May_323 May_452 Jun_323 Jun_452
#1 1995    31.3    16.2    25.2    20.1    19.0    31.2    15.0    12.2    12.0    12.5    10.1    22.1
#2 1996    28.0    14.3    20.2    23.1    17.5    34.2    14.0    14.2    10.5    13.5    12.2    19.1
#3 1997    20.2    20.1    22.1    22.1    31.2    32.2    12.2    13.2    12.5    11.5    22.1    18.1

数据

df1 <- structure(list(Station.ID = c(323L, 323L, 323L, 452L, 452L, 452L
), Year = c(1995L, 1996L, 1997L, 1995L, 1996L, 1997L), Jan = c(31.3, 
28, 20.2, 16.2, 14.3, 20.1), Feb = c(25.2, 20.2, 22.1, 20.1, 
23.1, 22.1), Mar = c(19, 17.5, 31.2, 31.2, 34.2, 32.2), Apr = c(15, 
14, 12.2, 12.2, 14.2, 13.2), May = c(12, 10.5, 12.5, 12.5, 13.5, 
11.5), Jun = c(10.1, 12.2, 22.1, 22.1, 19.1, 18.1)), .Names = c("Station.ID", 
"Year", "Jan", "Feb", "Mar", "Apr", "May", "Jun"), class = "data.frame", row.names = c(NA, 
 -6L))