The R Project SVN – R – Diff – /trunk/src/main/array.c

 	    for (i = 0; i < n; i++) pp[i] = INTEGER(perm)[i] - 1;
 	    UNPROTECT(1);
+	}
+    }
+    /* handle the resize */
+    int resize = asLogical(CADDR(args));
+    if (resize == NA_LOGICAL) error(_("'resize' must be TRUE or FALSE"));
+    /* short-circuit identity permutation (PR#19069) */
+    if(resize) {
+	bool skip = true;
+        for (i = 0; i < n; i++) if (pp[i] != i) {skip = false; break;}
+        if (skip) {UNPROTECT(1); return(a);}
+    }
     R_xlen_t *iip = (R_xlen_t *) R_alloc((size_t) n, sizeof(R_xlen_t));
     Memzero(iip, n);
     for (i = 0; i < n; i++)
 	if (pp[i] >= 0 && pp[i] < n) iip[pp[i]]++;
 	else error(_("value out of range in 'perm'"));
     default:
 	UNIMPLEMENTED_TYPE("aperm", a);
+    }
-    /* handle the resize */
-    int resize = asLogical(CADDR(args));
-    if (resize == NA_LOGICAL) error(_("'resize' must be TRUE or FALSE"));
-    /* and handle names(dim(.)) and the dimnames if any */
+    /* handle names(dim(.)) and the dimnames if any */
     if (resize) {
 	SEXP nmdm = getAttrib(dimsa, R_NamesSymbol);
 	if(nmdm != R_NilValue) { // dimsr needs correctly permuted names()
 	    PROTECT(nmdm);
 	    SEXP nm_dr = PROTECT(allocVector(STRSXP, n));

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