names-attribute concept

concepts/names-attribute/.meta/config.json

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+{
+  "authors": ["colinleach"],
+  "contributors": [],
+  "blurb": "Adding names to vector elements can make them more convenient to work with"
+}

concepts/names-attribute/about.md

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+# About
+
+Vectors can have named elements, which sometimes makes them more convenient to work with.
+
+## Creation
+
+There are three ways to add names to a vector.
+
+1) At vector creation time 
+
+```R
+> work_days <- c(Mon = TRUE, Tue = TRUE, Wed = TRUE, Thu = TRUE, Fri = TRUE, Sat = FALSE, Sun = FALSE)
+> work_days
+  Mon   Tue   Wed   Thu   Fri   Sat   Sun 
+ TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE 
+```
+
+2) By assigning a character vector to `names()`
+
+```R
+> months <- c(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+> names(months) <- month.abb
+> months
+Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
+ 31  28  31  30  31  30  31  31  30  31  30  31 
+```
+
+3) With `setNames()`
+
+```R
+> months <- c(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+> setNames(months, month.name)
+  January  February     March     April       May      June      July    August September   October  November  December 
+       31        28        31        30        31        30        31        31        30        31        30        31 
+```
+
+## Removal
+
+If names are no longer wanted they can be removed by setting to `NULL`
+
+```R
+> work_days
+  Mon   Tue   Wed   Thu   Fri   Sat   Sun 
+ TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE 
+> names(work_days) <- NULL
+> work_days
+[1]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE
+```
+
+The `unname()` function achieves the same thing, and may make your intention clearer.
+
+## Working with names
+
+The `names()` function can retrieve names as well as set them.
+
+```R
+> names(months) <- month.abb
+> names(months)[1:3]
+[1] "Jan" "Feb" "Mar"
+```
+
+A name can be used in place of the position index, with quotes required in this case.
+
+```R
+> months[c("Jul", "Aug")]
+Jul Aug 
+ 31  31 
+```
+
+For this reason it is best to ensure that names are unique and non-missing, though R does not enforce this.
+
+The usual vector operations still work, and names usually will be preserved if that makes sense.
+
+```R
+> months[months == 30]
+Apr Jun Sep Nov 
+ 30  30  30  30 
+
+> sum(months)
+[1] 365  # no meaningful names possible
+```
+
+## More advanced topics
+
+Many R objects, including `vectors`, can have arbitrary attributes attached to them. The `names` attribute is just one example, though a particularly common and important one.
+
+In practice, names are sometimes useful for vectors but rarely essential. the `names-attribute` becomes much more important for more complex structures such as `lists` and `dataframes`, as we shall see in future concepts.

concepts/names-attribute/introduction.md

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+# Introduction
+
+Vectors can have named elements, which sometimes makes them more convenient to work with.
+
+## Creation
+
+There are three ways to add names to a vector.
+
+1) At vector creation time 
+
+```R
+> work_days <- c(Mon = TRUE, Tue = TRUE, Wed = TRUE, Thu = TRUE, Fri = TRUE, Sat = FALSE, Sun = FALSE)
+> work_days
+  Mon   Tue   Wed   Thu   Fri   Sat   Sun 
+ TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE 
+```
+
+2) By assigning a character vector to `names()`
+
+```R
+> months <- c(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+> names(months) <- month.abb
+> months
+Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
+ 31  28  31  30  31  30  31  31  30  31  30  31 
+```
+
+3) With `setNames()`
+
+```R
+> months <- c(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+> setNames(months, month.name)
+  January  February     March     April       May      June      July    August September   October  November  December 
+       31        28        31        30        31        30        31        31        30        31        30        31 
+```
+
+## Removal
+
+If names are no longer wanted they can be removed by setting to `NULL`
+
+```R
+> work_days
+  Mon   Tue   Wed   Thu   Fri   Sat   Sun 
+ TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE 
+> names(work_days) <- NULL
+> work_days
+[1]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE
+```
+
+The `unname()` function achieves the same thing, and may make your intention clearer.
+
+## Working with names
+
+The `names()` function can retrieve names as well as set them.
+
+```R
+> names(months) <- month.abb
+> names(months)[1:3]
+[1] "Jan" "Feb" "Mar"
+```
+
+A name can be used in place of the position index, with quotes required in this case.
+
+```R
+> months[c("Jul", "Aug")]
+Jul Aug 
+ 31  31 
+```
+
+For this reason it is best to ensure that names are unique and non-missing, though R does not enforce this.
+
+The usual vector operations still work, and names usually will be preserved if that makes sense.
+
+```R
+> months[months == 30]
+Apr Jun Sep Nov 
+ 30  30  30  30 
+
+> sum(months)
+[1] 365  # no meaningful names possible
+```

concepts/names-attribute/links.json

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+[
+    {
+      "url": "https://adv-r.hadley.nz/vectors-chap.html#attr-names",
+      "description": "Advanced R: vector names"
+    }
+  ]

config.json

@@ -586,6 +586,11 @@
       "uuid": "2751b6f2-7d71-4397-b063-9bf927a57756",
       "slug": "booleans",
       "name": "Booleans"
+    },
+    {
+      "uuid": "be04c596-32c4-497f-9f56-7d939fe7890f",
+      "slug": "names-attribute",
+      "name": "Names Attribute"
     }
   ],
   "key_features": [