`R/sparse_casters.R`

`cast_sparse.Rd`

This function supports non-standard evaluation through the tidyeval framework.

`cast_sparse(data, row, column, value, ...)`

- data
A tbl

- row
Column name to use as row names in sparse matrix, as string or symbol

- column
Column name to use as column names in sparse matrix, as string or symbol

- value
Column name to use as sparse matrix values (default 1) as string or symbol

- ...
Extra arguments to pass on to

`sparseMatrix()`

A sparse Matrix object, with one row for each unique value in
the `row`

column, one column for each unique value in the `column`

column, and with as many non-zero values as there are rows in `data`

.

Note that cast_sparse ignores groups in a grouped tbl_df. The arguments
`row`

, `column`

, and `value`

are passed by expression and support
quasiquotation; you can unquote strings and symbols.

```
dat <- data.frame(a = c("row1", "row1", "row2", "row2", "row2"),
b = c("col1", "col2", "col1", "col3", "col4"),
val = 1:5)
cast_sparse(dat, a, b)
#> 2 x 4 sparse Matrix of class "dgCMatrix"
#> col1 col2 col3 col4
#> row1 1 1 . .
#> row2 1 . 1 1
cast_sparse(dat, a, b, val)
#> 2 x 4 sparse Matrix of class "dgCMatrix"
#> col1 col2 col3 col4
#> row1 1 2 . .
#> row2 3 . 4 5
```