add test-examples

DESCRIPTION

@@ -47,7 +47,7 @@ Description:
       <doi:10.1037/1082-989X.9.3.275>.
       "Structural equation models of latent interactions: evaluation of alternative estimation strategies and indicator construction."
     Muthén, L.K. and Muthén, B.O. (1998-2017).  
-      "'Mplus' User’s Guide.  Eighth Edition."
+      "'Mplus' User’s Guide. Eighth Edition."
       <https://www.statmodel.com/>.
     Rosseel Y (2012). 
       <doi:10.18637/jss.v048.i02>.
@@ -58,7 +58,7 @@ LazyData: true
 RoxygenNote: 7.3.2
 LinkingTo: Rcpp, RcppArmadillo
 Imports: Rcpp, purrr, stringr, lavaan, rlang, MplusAutomation, nlme, dplyr, 
-  mvnfast, stats, fastGHQuad, mvtnorm, ggplot2, parallel
+  mvnfast, stats, fastGHQuad, mvtnorm, ggplot2, parallel, plotly
 Depends: 
     R (>= 3.5.0)
 URL: https://modsem.org

NAMESPACE

@@ -75,6 +75,7 @@ export(multiplyIndicatorsCpp)
 export(parameter_estimates)
 export(plot_interaction)
 export(plot_jn)
+export(plot_surface)
 export(standardized_estimates)
 export(trace_path)
 export(var_interactions)

tests/testthat/test_lms.R

@@ -17,6 +17,7 @@ est1 <- modsem(m1, oneInt, method = "lms", optimize = TRUE, verbose = TRUE,
                convergence = 1e-2, R.max = 50000)
 plot_interaction("X", "Z", "Y", "X:Z", -3:3, c(-0.5, 0.5), est1)
 print(summary(est1, adjusted.stat = TRUE))
+plot_surface(x = "X", z = "Z", y = "Y", model = est1)
 
 # PROBLEM:
 #   I have no clue why, but changing the ordering of how the interaction terms 

tests/testthat/test_qml.R

@@ -12,7 +12,8 @@ est1 <- modsem(m1, data = oneInt, convergence = 1e-2, method = "qml",
                robust.se = TRUE)
 print(summary(est1, scientific = TRUE))
 plot_interaction(x = "X", z = "Z", y = "Y", xz = "X:Z", vals_z = c(-0.5, 0.5), model = est1)
-plot_surface(x = "X", z = "Z", y = "Y", model = est)
+plot_surface(x = "X", z = "Z", y = "Y", model = est1)
+
 
 tpb <- ' 
 # Outer Model (Based on Hagger et al., 2007)

vignettes/plot_interactions.Rmd

@@ -43,7 +43,8 @@ m1 <- "
   Y ~ X + Z + X:Z
 "
 est1 <- modsem(m1, data = oneInt)
-plot_interaction("X", "Z", "Y", "X:Z", vals_z = -3:3, range_y = c(-0.2, 0), model = est1)
+plot_interaction("X", "Z", "Y", "X:Z", vals_z = -3:3, 
+                 range_y = c(-0.2, 0), model = est1)
 ```
 
 Here is a different example using the `lms` approach in the theory of planned behavior model:
@@ -91,13 +92,12 @@ m1 <-  '
   visual ~ speed + textual + speed:textual
 '
 
-est <- modsem(m1, data = lavaan::HolzingerSwineford1939, method = "ca")
-plot_jn(x = "speed", z = "textual", y = "visual", model = est, max_z = 6)
+est1 <- modsem(m1, data = lavaan::HolzingerSwineford1939, method = "ca")
+plot_jn(x = "speed", z = "textual", y = "visual", model = est1, max_z = 6)
 ```
 
 Here is another example using the `qml` approach in the theory of planned behavior model:
 ```{r}
-
 tpb <- "
 # Outer Model (Based on Hagger et al., 2007)
   ATT =~ att1 + att2 + att3 + att4 + att5
@@ -113,7 +113,31 @@ tpb <- "
 "
 
 est2 <- modsem(tpb, TPB, method = "qml")
-plot_jn(x = "INT", z = "PBC", y = "BEH", model = est2,
-                    min_z = -1.5, max_z = -0.5)
+plot_jn(x = "INT", z = "PBC", y = "BEH", model = est2, 
+        min_z = -1.5, max_z = -0.5)
 ```
 
+# Plotting (3D) Surface Plots
+The `plot_surface()` function can be used to plot 3D surface plots for a given interaction effect.
+This function takes a fitted model object, the names of the two variables that are interacting,
+and the name of the dependent variable. The function will plot the 3D surface plot for the interaction effect.
+
+```{r}
+tpb <- "
+# Outer Model (Based on Hagger et al., 2007)
+  ATT =~ att1 + att2 + att3 + att4 + att5
+  SN =~ sn1 + sn2
+  PBC =~ pbc1 + pbc2 + pbc3
+  INT =~ int1 + int2 + int3
+  BEH =~ b1 + b2
+
+# Inner Model (Based on Steinmetz et al., 2011)
+  INT ~ ATT + SN + PBC
+  BEH ~ INT + PBC
+  BEH ~ PBC:INT
+"
+
+est2 <- modsem(tpb, TPB, method = "qml")
+
+plot_surface(x = "X", z = "Z", y = "Y", model = est1)
+```