Merge pull request #398 from lucdw/master

Allow autoregression if coeff. fixed to zero

Author: yrosseel

R/lav_syntax_parser.R

@@ -903,15 +903,6 @@ ldw_parse_model_string <- function(model.syntax = "", as.data.frame. = FALSE) {
         footer = tl[2L]
       )
     }
-       # check for variable regressed on itself
-    if (formul1$elem.text[opi] == "~" && formul1$elem.text[opi - 1L] == formul1$elem.text[nelem]) {
-        tl <- ldw_txtloc(modelsrc, formul1$elem.pos[opi])
-        lav_msg_stop(
-          gettext("a variable cannot be regressed on itself"),
-          tl[1L],
-          footer = tl[2L]
-        )
-      }
     # checks for valid names in lhs and rhs
     ldw_parse_check_valid_name(formul1, opi - 1L, modelsrc) # valid name lhs
     for (j in seq.int(opi + 1L, nelem)) { # valid names rhs
@@ -1101,6 +1092,18 @@ ldw_parse_model_string <- function(model.syntax = "", as.data.frame. = FALSE) {
         }
       }
     }
+    # check for variable regressed on itself
+    if (formul1$elem.text[opi] == "~" && 
+        formul1$elem.text[opi - 1L] == formul1$elem.text[nelem]) {
+      if (!grepl("^0\\.?0*$", flat.fixed[idx])) {
+        tl <- ldw_txtloc(modelsrc, formul1$elem.pos[opi])
+        lav_msg_stop(
+          gettext("a variable cannot be regressed on itself"),
+          tl[1L],
+          footer = tl[2L]
+        )
+      }
+    }
   }
   # create flat (omit items without operator)
   filled.ones <- which(flat.op != "")

R/lav_syntax_parser_r.R

@@ -797,9 +797,6 @@ lav_parse_model_string_r <- function(model.syntax = "", as.data.frame. = FALSE)
     if (length(contsp) > 0L) {
       lav_local_msgcode(FALSE, 102L, formul1$elem.pos[contsp[1L]], msgenv)
     }
-    # check for variable regressed on itself
-    if (formul1$elem.text[opi] == "~" && formul1$elem.text[opi - 1L] == formul1$elem.text[nelem])
-            return(c(34L, formul1$elem.pos[opi] - 1L))
     # checks for valid names in lhs and rhs
     lav_parse_check_valid_name(formul1, opi - 1L, modelsrc, msgenv) # valid name lhs
     if (exists("error", envir = msgenv)) return(msgenv$error);
@@ -969,6 +966,10 @@ lav_parse_model_string_r <- function(model.syntax = "", as.data.frame. = FALSE)
         }
       }
     }
+    # check for variable regressed on itself
+    if (formul1$elem.text[opi] == "~" && 
+        formul1$elem.text[opi - 1L] == formul1$elem.text[nelem])
+      if (!grepl("^0\\.?0*$", flat.fixed[idx])) return(c(34L, formul1$elem.pos[opi] - 1L))
   }
   # create flat (omit items without operator)
   filled.ones <- which(flat.op != "")