{"id":793,"date":"2018-05-18T23:32:54","date_gmt":"2018-05-18T21:32:54","guid":{"rendered":"https:\/\/blogs.fu-berlin.de\/reseda\/?page_id=793"},"modified":"2018-09-25T10:27:52","modified_gmt":"2018-09-25T08:27:52","slug":"e02","status":"publish","type":"page","link":"https:\/\/blogs.fu-berlin.de\/reseda\/e02\/","title":{"rendered":"R – Exercise II"},"content":{"rendered":"

1) Create an integer variable e<\/span> holding the value 42<\/span>! Check the object class of e<\/span> with class()<\/span>!<\/p>\n

\r\ne <- 42L\r\n\r\nclass(e)\r\n## [1] "integer"\r\n<\/pre>\n
2) Convert e<\/span> to the character data type with as.character()<\/span>! Check the object class again!<\/p>\n
\r\ne <- as.character(e)\r\n\r\nclass(e)\r\n## [1] "character"\r\n<\/pre>\n
3) Create a character vector friends<\/span> with four names from your circle of friends or acquaintances!<\/p>\n
\r\nfriends <- c("Anna", "Otto", "Natan", "Ede")\r\n\r\nfriends\r\n## [1] "Anna"  "Otto"  "Natan" "Ede"\r\n<\/pre>\n
4) Index the second element from the vector friends<\/span>!<\/p>\n
\r\nfriends[2]\r\n## [1] \"Otto\"\r\n<\/pre>\n
5) Replace the first element of the vector friends<\/span> with “Isolde” and check the updated vector again!<\/p>\n
\r\nfreunde[1] <- "Isolde"\r\n\r\nfreunde\r\n## [1] "Isolde" "Otto"   "Natan"  "Ede"\r\n<\/pre>\n
6) Create a vector v1<\/span> from the following elements  1, “Hello”, 2, “World” <\/span>! Check the object class!<\/p>\n
\r\nv1 <- c(1, "Hello", 2, "World")\r\n\r\nv1\r\n## [1] "1"     "Hello" "2"     "World"\r\n\r\nclass(v1)\r\n## [1] "character"\r\n<\/pre>\n
7) Create a vector v2 with numerical values \u200b\u200b(only integers) ranging from 4 to 10!<\/p>\n
\r\nv2 <- c(4, 5, 6, 7, 8, 9, 10)\r\n\r\nv2\r\n## [1]  4  5  6  7  8  9 10\r\n\r\n# or use the sequence operator ":"\r\n\r\nv2 <- c(4:10)\r\n\r\nv2\r\n## [1]  4  5  6  7  8  9 10\r\n<\/pre>\n
8) Index the first three elements from v2<\/span>!<\/p>\n
\r\nv2[1:3]\r\n## [1] 4 5 6\r\n\r\n# or:\r\n\r\nv2[ c(1, 2, 3) ]\r\n## [1] 4 5 6\r\n<\/pre>\n
9) Index all elements of v2<\/span> except the second element and save the result as v2.subset<\/span>!<\/p>\n
\r\nv2.subset <- v2[-2]\r\n\r\nv2.subset\r\n## [1]  4  6  7  8  9 10\r\n<\/pre>\n
10) Use the length () function to find out the length of v2.subset<\/span> (= the number of elements in the vector)!<\/p>\n
\r\nlength(v2.subset)\r\n## [1] 6\r\n<\/pre>\n
11) Calculate the arithmetic mean of vector v2<\/span>! In addition, determine the standard deviation of v2.subset<\/span>!<\/p>\n
\r\nmean(v2)\r\n## [1] 7\r\n\r\nsd(v2.subset)\r\n## [1] 2.160247\r\n<\/pre>\n
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