Expand Grid for only certain parts of a datafame-CodePudding

I have a dataframe in R that looks like this:

head(pitch_type_df)
# A tibble: 6 x 20
# Groups:   player_name, pitcher [3]
  player_name pitcher pitch~1 relea~2 relea~3 pfx_x~4  pfx_z relea~5 relea~6 relea~7 spin_~8 spin_~9 velo_~*
  <chr>         <dbl> <chr>     <dbl>   <dbl>   <dbl>  <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>
1 Abbott, Co~  676265 FF         91.3   2253. -0.959   1.43    -2.60    5.48    6.27   0.837   219.     0   
2 Abbott, Co~  676265 KC         84.4   2291.  0.0784 -0.459   -2.48    5.85    6.01   0.220    39.9   -6.93
3 Abbott, Co~  676265 SL         86.6   2133. -0.852   0.486   -2.47    5.88    6.06   0.390   225.    -4.85
4 Abreu, Alb~  656061 SI         98.5   2200. -1.22    1.10    -1.71    5.69    6.62   0.874   220.     0   
5 Abreu, Alb~  656061 SL         88.6   2265.  0.209   0.457   -2.05    5.74    6.43   0.145   190.    -9.76

I would like to implement some way to use expand_grid to add two columns, plate_x and plate_z, that are sequences from -1.75 to 1.75 and 0 to 4.5, respectively. How can I add this to my dataframe in a way that a grid is created from the sequenced values to get a dataframe with all unique combinations of plate_x and plate_z for each row, without it putting together a grid with unique combinations of all the other columns? The grid to be combined with the original for each row would look like this:

expand_grid(plate_x = seq(-1.75, 1.75, by = .1), plate_z = seq(0, 4.25, by = .1))
# A tibble: 1,548 x 2
   plate_x plate_z
     <dbl>   <dbl>
 1   -1.75     0  
 2   -1.75     0.1
 3   -1.75     0.2
 4   -1.75     0.3
 5   -1.75     0.4
 6   -1.75     0.5
 7   -1.75     0.6
 8   -1.75     0.7
 9   -1.75     0.8
10   -1.75     0.9
# ... with 1,538 more rows
# i Use `print(n = ...)` to see more rows

My end product would be each row from the first dataframe added to this grid, for each row.

CodePudding user response：

We may use crossing

library(tidyr)
crossing(pitch_type_df,
    expand_grid(plate_x = seq(-1.75, 1.75, by = .1), 
    plate_z = seq(0, 4.25, by = .1)))