From e3553bd4821f8fd971cd3bed37123fb4815fb9a2 Mon Sep 17 00:00:00 2001
From: "Thomas J. Leeper" <thosjleeper@gmail.com>
Date: Mon, 23 Jul 2018 11:05:40 +0100
Subject: [PATCH] coerce data to cj_df in cj()

---
 DESCRIPTION    | 4 ++--
 NEWS.md        | 4 ++++
 R/amce_diffs.R | 3 +++
 R/cj.R         | 3 +++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 703bfec..84247b5 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: cregg
 Type: Package
 Title: Simple Conjoint Tidying, Analysis, and Visualization
-Version: 0.2.3
-Date: 2018-07-10
+Version: 0.2.4
+Date: 2018-07-23
 Authors@R: c(person("Thomas J.", "Leeper", role = c("aut", "cre"),
                     email = "thosjleeper@gmail.com",
                     comment = c(ORCID = "0000-0003-4097-6326")))
diff --git a/NEWS.md b/NEWS.md
index 89cf6a6..ee105e9 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,7 @@
+# cregg 0.2.4
+
+* `cj()` now imposes class "cj_df" on `data` to preserve attributes during subsetting.
+
 # cregg 0.2.3
 
 * Added function `cj_table()`, which can be useful in communicating the set of features and levels used in the design as a data frame (e.g,. using `knitr::kable(cj_table(data, ~ feat1 + feat2))`).
diff --git a/R/amce_diffs.R b/R/amce_diffs.R
index 8b007a5..aa4d001 100644
--- a/R/amce_diffs.R
+++ b/R/amce_diffs.R
@@ -68,6 +68,9 @@ function(
   ...
 ) {
     
+    # coerce to "cj_df" to preserve attributes
+    data <- cj_df(data)
+    
     # get outcome variable
     outcome <- all.vars(stats::update(formula, . ~ 0))
     
diff --git a/R/cj.R b/R/cj.R
index 221f70b..a9015de 100644
--- a/R/cj.R
+++ b/R/cj.R
@@ -15,6 +15,9 @@ function(
 ) {
     estimate <- match.arg(estimate)
     
+    # coerce to "cj_df" to preserve attributes
+    data <- cj_df(data)
+    
     if (!is.null(by)) {
         # get RHS variables, variable labels, and factor levels
         RHS <- all.vars(stats::update(formula, 0 ~ . ))