Switch

concepts/switch/.meta/config.json

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+{
+  "authors": ["colinleach"],
+  "contributors": [],
+  "blurb": "If matching on a value, especially a string, switch() can be more concise than if-else."
+}

concepts/switch/about.md

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+# About
+
+The `switch()` function can be a concise replacement for a long series of `if` ... `else if` tests.
+The variable being switched on is most commonly a string, and if so the quotes can be omitted from the selector.
+
+```R
+star <- function(type) {
+  switch(type,
+    M = , # will "fall through" if no value given
+    K = "red dwarf",
+    G = "Earth-like",
+    "bigger star" # only correct for O,B,A,F
+  )
+}
+
+> star("M")
+[1] "red dwarf"
+```
+
+Note that options will only fall through if the value is left blank, as with `M` in the example above. 
+There is no need to include `break` statements as with some other languages.
+
+The final value can be a default, as here, or a `stop()` to throw an error if the conditions are intended to be exhaustive.
+Switching on an integer is slightly different: for these the default is always `NULL`.

concepts/switch/introduction.md

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+# Introduction
+
+The `switch()` function can be a concise replacement for a long series of `if` ... `else if` tests.
+The variable being switched on is most commonly a string, and if so the quotes can be omitted from the selector.
+
+```R
+star <- function(type) {
+  switch(type,
+    M = , # will "fall through" if no value given
+    K = "red dwarf",
+    G = "Earth-like",
+    "bigger star" # only correct for O,B,A,F
+  )
+}
+
+> star("M")
+[1] "red dwarf"
+```
+
+Note that options will only fall through if the value is left blank, as with `M` in the example above. 
+There is no need to include `break` statements as with some other languages.
+
+With character types, the final value can be a default, as here, or a `stop()` to throw an error if the conditions are intended to be exhaustive.
+Switching on an integer is slightly different: for these the default is always `NULL`.

concepts/switch/links.json

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+[
+  {
+    "url": "https://adv-r.hadley.nz/control-flow.html#switch",
+    "description": "Advanced R, 2nd ed: switch"
+  }
+]

config.json

@@ -569,6 +569,11 @@
       "uuid": "2751b6f2-7d71-4397-b063-9bf927a57756",
       "slug": "booleans",
       "name": "Booleans"
+    },
+    {
+      "uuid": "e4c75b26-aacf-4598-a12b-88e0257bd3f5",
+      "slug": "switch",
+      "name": "Switch"
     }
   ],
   "key_features": [