vector-functions concept

concepts/vector-functions/.meta/config.json

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+{
+  "authors": ["colinleach"],
+  "contributors": [],
+  "blurb": "Many R functions can operate on entire vectors without the need for explicit loops."
+}

concepts/vector-functions/about.md

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+# About
+
+This is a big concept in R.
+To help make sense of the possibilities, it can be useful to consider the dimensionality of the input(s) and output of the various functions.
+
+## Vector-in, scalar-out
+
+We already saw functions that take in a vector and return a single, scalar-like value:
+
+```R
+> v <- 1:5
+> sum(v)
+[1] 15
+> length(v)
+[1] 5
+```
+
+Many statistical functions are also in this category, such as `mean()`.
+
+For logical vectors, there are `all()` and `any()`, which return a single `TRUE` or `FALSE`.
+
+## Vector-in, vector-out
+
+Many functions in R will operate on entire vectors, often giving vector output.
+This includes most of the mathematical functions:
+
+```R
+> sq <- c(4, 9, 16, 25)
+> sqrt(sq) # square root
+[1] 2 3 4 5
+```
+
+This is not just concise and convenient, avoiding the need for loops, list comprehensions or recursion.
+In R, vector functions often run much faster than these more familiar techniques.
+
+You already used vectorized functions more than you probably realized. Compare these:
+
+```R
+> v <- c(2, 7, 9)
+> w <- c(3, 1, 5)
+> v + w
+[1]  5  8 14
+> "+"(v, w)
+[1]  5  8 14
+```
+
+The familiar infix operators are just syntactic sugar for the underlying vectorized function! In this case `"+"()`.
+
+For sorting a vector, there is `sort()` to return the values and `order()` to return the indices:
+
+```R
+> v <- c("I", "am", "not", "in", "order")
+> sort(v)
+[1] "am"    "I"     "in"    "not"   "order"
+> order(v)
+[1] 2 1 4 3 5
+```
+
+There are also functions to produce cumulative vector outputs, operating on the input vector left-to-right:
+
+```R
+> cumsum(1:5)
+[1]  1  3  6 10 15  # sums
+> cumprod(1:5)
+[1]   1   2   6  24 120 # factorials, for a range like this
+```
+
+## Multiple-vectors-in, vector-out
+
+An extension of this concept can also be used to compare vectors.
+For example, consider the pairwise-max function `pmax()`:
+
+```R
+> v
+[1] 2 7 9
+> w
+[1] 3 1 5
+> pmax(v, w)
+[1] 3 7 9 # max of each pairwise comparison
+```
+
+This function and others like it also accept an arbitrary number of input vectors, not just two.
+
+## Vector-in, matrix-out
+
+Less common, but it is fairly easy to write functions that are apparently scalar-in, vector out.
+When applied to vector input, the output is a 2-D `matrix` (covered in a later concept).

concepts/vector-functions/introduction.md

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+# Introduction
+
+This is a big concept in R.
+To help make sense of the possibilities, it can be useful to consider the dimensionality of the input and output of the various functions.
+
+## Vector-in, scalar-out
+
+We already saw functions that take in a vector and return a single, scalar-like value:
+
+```R
+> v <- 1:5
+> sum(v)
+[1] 15
+> length(v)
+[1] 5
+```
+
+Many statistical functions are also in this category, such as `mean()`.
+
+For logical vectors, there are `all()` and `any()`.
+
+## Vector-in, vector-out
+
+Many functions in R will operate on entire vectors, often giving vector output.
+This includes most of the mathematical functions:
+
+```R
+> sq <- c(4, 9, 16, 25)
+> sqrt(sq) # square root
+[1] 2 3 4 5
+```
+
+This is not just concise and convenient, avoiding the need for loops, list comprehensions or recursion.
+In R, vector functions often run much faster than these more familiar techniques.
+
+For sorting a vector, there is `sort()` to return the values and `order()` to return the indices:
+
+```R
+> v <- c("I", "am", "not", "in", "order")
+> sort(v)
+[1] "am"    "I"     "in"    "not"   "order"
+> order(v)
+[1] 2 1 4 3 5
+```
+
+There are also functions to produce cumulative vector outputs, operating on the input vector left-to-right:
+
+```R
+> cumsum(1:5)
+[1]  1  3  6 10 15  # sums
+> cumprod(1:5)
+[1]   1   2   6  24 120 # factorials, for a range like this
+```
+
+## Multiple-vectors-in, vector-out
+
+An extension of this concept can also be used to compare vectors.
+For example, consider the pairwise-max function `pmax()`:
+
+```R
+> v
+[1] 2 7 9
+> w
+[1] 3 1 5
+> pmax(v, w)
+[1] 3 7 9 # max of each pairwise comparison
+```

concepts/vector-functions/links.json

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+[
+  {
+    "url": "https://intro2r.com/using-functions-in-r.html",
+    "description": "Functions in R"
+  },
+  {
+    "url": "https://intro2r.com/vectors.html#vec_ord",
+    "description": "Ordering vectors"
+  },
+  {
+    "url": "https://intro2r.com/vectors.html#vectorisation",
+    "description": "Vectorisation"
+  }
+]

config.json

@@ -586,6 +586,11 @@
       "uuid": "2751b6f2-7d71-4397-b063-9bf927a57756",
       "slug": "booleans",
       "name": "Booleans"
+    },
+    {
+      "uuid": "68d54762-d212-4e4c-b2b7-815acd13de2c",
+      "slug": "vector-functions",
+      "name": "Vector Functions"
     }
   ],
   "key_features": [