fit_xy changes and some docs

Author: topepo

NEWS.md

@@ -1,3 +1,12 @@
+# parsnip 0.0.2.9000
+
+## New Features
+
+ * `add_rowindex()` can create a column called `.row` to a data frame. 
+ 
+ * If a computational engine is not explicitly set, a default will be used. Each default is documented on the corresponding model page. A warning is issued at fit time unless verbosity is zero.  
+
+
 # parsnip 0.0.2
 
 Small release driven by changes in `sample()` in the current r-devel. 

R/fit.R

@@ -186,8 +186,13 @@ fit_xy.model_spec <-
            ...
   ) {
     dots <- quos(...)
-    if (any(names(dots) == "engine"))
-      stop("Use `set_engine()` to supply the engine.", call. = FALSE)
+    if (is.null(object$engine)) {
+      eng_vals <- possible_engines(object)
+      object$engine <- eng_vals[1]
+      if (control$verbosity > 0) {
+        warning("Engine set to `", object$engine, "`", call. = FALSE)
+      }
+    }
 
     if (object$engine != "spark" & NCOL(y) == 1 & !(is.vector(y) | is.factor(y))) {
       if (is.matrix(y)) {

_pkgdown.yml

@@ -32,6 +32,7 @@ reference:
       - svm_rbf
   - title: Infrastructure
     contents:
+      - add_rowindex
       - descriptors
       - fit.model_spec
       - fit_xy