class: monash-bg-blue center middle hide-slide-number <div class="bg-black white" style="width:45%;right:0;bottom:0;padding-left:5px;border: solid 4px white;margin: auto;"> <i class="fas fa-exclamation-circle"></i> These slides are viewed best by Chrome and occasionally need to be refreshed if elements did not load properly. See here for <a href=day1-session3.pdf>PDF <i class="fas fa-file-pdf"></i></a>. </div> <br> .white[Press the **right arrow** to progress to the next slide!] --- count: false background-image: url(images/bg1.jpg) background-size: cover class: hide-slide-number title-slide <div class="grid-row" style="grid: 1fr / 2fr;"> .item.center[ # <span style="text-shadow: 2px 2px 30px white;">Data Wrangling with R: Day 1</span> <!-- ## <span style="color:;text-shadow: 2px 2px 30px black;">Manipulating strings with `stringr`</span> --> ] .center.shade_black.animated.bounceInUp.slower[ <br><br> ## <span style="color: #ccf2ff; text-shadow: 10px 10px 100px white;">Manipulating strings with `stringr`</span> <br> Presented by Emi Tanaka Department of Econometrics and Business Statistics <img src="images/monash-one-line-reversed.png" style="width:500px"><br> <span><i class="fas fa-envelope faa-float animated "></i></span> emi.tanaka@monash.edu <span><i class="fab fa-twitter faa-float animated faa-fast "></i></span> @statsgen .bottom_abs.width100.bg-black[ 1st December 2020 @ Statistical Society of Australia | Zoom ] ] </div> --- # Manipulating strings * The `stringr` package is powered by the `stringi` package which in turn uses the [ICU](http://site.icu-project.org/) C library to provide fast peformance for string manipulation .footnote[ Hadley Wickham (2019). stringr: Simple, Consistent Wrappers for Common String Operations. R package version 1.4.0. Gagolewski M. and others (2020). R package stringi: Character string processing facilities. ] -- * Main functions in `stringr` **prefix with `str_`** (`stringi` prefix with `stri_`) and the **first argument is string** (or a vector of strings) -- * What do you think `str_trim` and `str_squish` do? ```r str_trim(c(" Apple ", " Goji Berry ")) ``` ``` ## [1] "Apple" "Goji Berry" ``` ```r str_squish(c(" Apple ", " Goji Berry ")) ``` ``` ## [1] "Apple" "Goji Berry" ``` --- # Base R and `stringr` <div id="htmlwidget-a60de4da7928d1a6d8b2" style="width:100%;height:auto;" class="datatables html-widget"></div> <script type="application/json" data-for="htmlwidget-a60de4da7928d1a6d8b2">{"x":{"filter":"none","data":[["gregexpr(pattern, x)","grep(pattern, x, value = TRUE)","grep(pattern, x)","grepl(pattern, x)","gsub(pattern, replacement, x)","nchar(x)","order(x)","regexec(pattern, x) + regmatches()","regexpr(pattern, x) + regmatches()","regexpr(pattern, x)","sort(x)","strrep(x, n)","strsplit(x, pattern)","strwrap(x)","sub(pattern, replacement, x)","substr(x, start, end)","tolower(x)","tools::toTitleCase(x)","toupper(x)","trimws(x)"],["str_locate_all(x, pattern)","str_subset(x, pattern)","str_which(x, pattern)","str_detect(x, pattern)","str_replace_all(x, pattern, replacement)","str_length(x)","str_order(x)","str_match(x, pattern)","str_extract(x, pattern)","str_locate(x, pattern)","str_sort(x)","str_dup(x, n)","str_split(x, pattern)","str_wrap(x)","str_replace(x, pattern, replacement)","str_sub(x, start, end)","str_to_lower(x)","str_to_title(x)","str_to_upper(x)","str_trim(x)"]],"container":"<table class=\"display\">\n <thead>\n <tr>\n <th>Base R<\/th>\n <th>stringr<\/th>\n <\/tr>\n <\/thead>\n<\/table>","options":{"lengthChange":false,"dom":"tp","columnDefs":[{"className":"dt-left"}],"order":[],"autoWidth":false,"orderClasses":false}},"evals":[],"jsHooks":[]}</script> .footnote[ See more at https://stringr.tidyverse.org/articles/from-base.html ] --- # Why use `stringr`? * There are a number of considerations to ensure there is consistency in syntax and user expectation (both for input and output) -- * For example, let's consider <u>combining multiple strings into one</u>. -- .grid[ .item[ **Base R** ```r paste0("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ] .item[ **`stringr`** ```r str_c("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ]] --- count: false # Why use `stringr`? * There are a number of considerations to ensure there is consistency in syntax and user expectation (both for input and output) * For example, let's consider <u>combining multiple strings into one</u>. .grid[ .item[ **Base R** ```r paste0("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ```r paste0("Area", "1", c("A", NA, "C")) ``` ] .item[ **`stringr`** ```r str_c("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ```r str_c("Area", "1", c("A", NA, "C")) ``` ]] --- count: false # Why use `stringr`? * There are a number of considerations to ensure there is consistency in syntax and user expectation (both for input and output) * For example, let's consider <u>combining multiple strings into one</u>. .grid[ .item[ **Base R** ```r paste0("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ```r paste0("Area", "1", c("A", NA, "C")) ``` ``` ## [1] "Area1A" "Area1NA" "Area1C" ``` ] .item[ **`stringr`** ```r str_c("Area", "1", c("A", "B")) ``` ``` ## [1] "Area1A" "Area1B" ``` ```r str_c("Area", "1", c("A", NA, "C")) ``` ``` ## [1] "Area1A" NA "Area1C" ``` ]] * If the Base R result is preferable then NA can be replaced with character with .monash-blue[`str_replace_na`]`("A", NA, "C")` first --- # .orange[Case study <i class="fas fa-search-plus"></i>] Aussie Local Government Area ```r LGA <- ozmaps::abs_lga %>% pull(NAME) LGA[1:7] ``` ``` ## [1] "Broken Hill (C)" "Waroona (S)" "Toowoomba (R)" "West Arthur (S)" ## [5] "Moreton Bay (R)" "Etheridge (S)" "Cleve (DC)" ``` <center> <table style="width:90%"> <tr> <td>C = Cities</td> <td>A = Areas</td> <td>RC = Rural Cities</td> </tr> <tr> <td>B = Boroughs</td> <td>S = Shires</td> <td>DC = District Councils</td> </tr> <tr> <td>M = Municipalities</td> <td>T = Towns</td> <td>AC = Aboriginal Councils </td> </tr> <tr> <td>RegC = Regional Councils</td> </tr> </table> </center> <br> .center[ 🎯 **Extract the LGA status from the LGA names** {{content}} ] .footnote[ Michael Sumner (2020). ozmaps: Australia Maps. R package version 0.3.6. ] -- How? --- name: lga # Extracting the string ```r str_extract(LGA, "\\(.+\\)") ``` ``` ## [1] "(C)" "(S)" "(R)" "(S)" "(R)" ## [6] "(S)" "(DC)" "(R)" "(DC)" "(C)" ## [11] "(DC)" "(S)" "(S)" "(S)" "(DC)" ## [16] "(A)" "(C)" "(A)" "(T)" "(RC)" ## [21] "(A)" "(S)" "(S)" "(S)" "(C)" ## [26] "(DC)" "(R)" "(A)" "(C)" "(DC)" ## [31] "(S)" "(S)" "(A)" "(S)" "(S)" ## [36] "(R)" "(M)" "(A)" "(C)" "(S)" ## [41] "(S)" "(C)" "(A)" "(S)" "(C)" ## [46] "(AC)" "(A)" "(S)" "(A)" "(C)" ## [51] "(A)" "(R)" "(S)" "(T)" "(C)" ## [56] "(S)" "(S)" "(R)" "(C)" "(T)" ## [61] "(C)" "(S)" "(C)" "(C)" "(C)" ## [66] "(C)" "(S)" "(DC)" "(DC)" "(S)" ## [71] "(R)" "(R)" "(S)" "(B)" "(DC)" ## [76] "(M)" "(A)" "(C)" "(S)" "(S)" ## [81] "(S)" "(S)" "(S)" "(S)" "(S)" ## [86] "(C)" "(A)" "(C)" "(A)" "(S)" ## [91] "(C)" "(A)" "(S)" "(S)" "(S)" ## [96] "(S)" "(DC)" "(S)" "(S)" "(S)" ## [101] "(C)" "(C)" "(DC)" "(S)" "(S)" ## [106] "(C)" "(S)" "(DC)" "(C)" "(C)" ## [111] "(S)" "(S)" "(S)" "(S)" "(S)" ## [116] "(S)" "(A)" "(DC)" "(S)" "(A)" ## [121] "(C)" "(A)" "(S)" "(A)" "(DC)" ## [126] "(S)" "(C)" "(S)" "(A)" "(S)" ## [131] "(M)" "(S)" "(DC)" "(R)" "(C)" ## [136] "(C)" "(S)" "(C)" "(S)" "(T)" ## [141] "(S)" "(S)" "(DC)" "(S)" "(T)" ## [146] "(C)" "(S)" "(M)" "(S)" "(DC)" ## [151] "(C)" "(S)" "(M)" "(C)" "(S)" ## [156] "(C)" "(C)" "(R)" "(S)" "(C)" ## [161] "(C)" "(R)" "(S)" "(C)" "(A)" ## [166] "(T)" "(S)" "(RC)" "(C)" "(A)" ## [171] "(A)" "(A)" "(S)" "(A)" "(S)" ## [176] "(S)" "(T)" "(S)" "(S)" "(S)" ## [181] "(A)" "(DC)" "(M)" "(C)" "(S)" ## [186] "(A)" "(T)" "(A)" "(C)" "(S)" ## [191] "(C)" "(R)" "(C)" "(S)" "(S)" ## [196] "(S)" "(S)" "(R)" "(C)" "(DC)" ## [201] "(A)" "(DC)" "(R)" "(C)" "(S)" ## [206] "(S)" "(C)" "(C)" "(R)" "(S)" ## [211] "(S)" "(C)" "(A)" "(S)" "(S)" ## [216] "(C)" "(DC)" "(S)" "(M) (Tas.)" "(M) (Tas.)" ## [221] "(C) (Vic.)" "(C) (Vic.)" "(S)" "(DC)" "(S)" ## [226] "(RC)" "(S)" "(DC)" "(S)" "(S)" ## [231] "(R)" "(S)" "(A)" "(C)" "(C)" ## [236] "(A)" "(A)" "(RC)" "(S)" "(C)" ## [241] "(S)" "(S)" "(S)" "(C)" "(C)" ## [246] "(S)" "(C)" "(C)" "(C)" "(A)" ## [251] "(C)" "(S)" "(S)" "(S)" "(S)" ## [256] "(S)" "(A)" "(A)" "(A)" "(S)" ## [261] "(A)" "(A)" "(S)" "(S)" "(C)" ## [266] "(A)" "(M)" "(S)" "(S)" "(C)" ## [271] "(R)" "(S)" "(R)" "(DC)" "(R)" ## [276] "(C)" "(S)" "(S)" "(C)" "(S)" ## [281] "(A)" "(R)" "(DC)" "(A)" "(C)" ## [286] "(A)" "(S)" "(S)" "(A)" "(C)" ## [291] "(C)" "(A)" "(T)" "(S)" "(C)" ## [296] "(A)" "(A)" "(S)" "(S)" "(T)" ## [301] "(C)" "(A)" "(A)" "(DC)" "(A)" ## [306] "(C)" "(M)" "(M)" "(S)" "(A)" ## [311] "(A)" "(C)" "(C)" "(S)" "(DC)" ## [316] "(S)" "(C)" "(S)" "(S)" "(DC)" ## [321] "(RegC)" "(C)" "(S)" "(S)" NA ## [326] "(A)" "(S)" "(A)" "(S)" "(A)" ## [331] "(S)" "(C)" "(R)" "(C)" "(S)" ## [336] "(A)" "(DC)" "(S)" "(A)" "(R)" ## [341] "(S)" "(S)" "(RC)" "(T)" "(A)" ## [346] "(M)" "(A)" "(S)" "(S)" "(S)" ## [351] "(S)" "(A)" "(RC)" "(S)" "(A)" ## [356] "(R)" "(S)" "(S)" "(C)" "(S)" ## [361] "(DC)" "(M)" "(M)" "(AC)" "(DC)" ## [366] "(A)" "(A)" "(S)" "(S)" "(A)" ## [371] "(C)" "(S)" "(S)" "(C)" "(R)" ## [376] "(S)" "(S)" NA "(A)" "(T)" ## [381] "(S)" "(A)" "(C)" "(C)" "(A)" ## [386] "(C)" "(DC)" "(C)" "(A)" "(A)" ## [391] "(A)" "(S)" "(DC)" "(DC)" "(S)" ## [396] "(M)" "(R)" "(DC)" "(C)" "(S)" ## [401] "(S)" "(C)" "(C)" "(C)" "(C)" ## [406] "(C)" "(S)" "(A)" NA "(S)" ## [411] "(C)" "(S)" "(M)" "(C)" "(S)" ## [416] "(S)" NA "(C)" "(S)" "(C)" ## [421] "(DC)" "(S)" "(C)" "(S)" "(C)" ## [426] "(M)" "(A)" "(A)" "(A)" "(S)" ## [431] "(C)" "(S)" "(S)" "(S)" "(A)" ## [436] "(A)" "(A)" "(S)" "(S)" "(S)" ## [441] "(C)" "(S)" "(C)" "(C)" "(C)" ## [446] "(C) (NSW)" "(S) (Qld)" "(R) (Qld)" "(DC) (SA)" "(C) (SA)" ## [451] "(M) (Tas.)" "(M) (Tas.)" "(C)" "(R)" "(M)" ## [456] "(C)" "(R)" "(S)" "(RC)" "(S)" ## [461] "(M)" "(C)" "(R)" "(C)" "(DC)" ## [466] "(C)" "(C)" "(M)" "(C)" "(S)" ## [471] "(C)" "(DC)" "(M)" "(S)" "(C)" ## [476] "(C)" "(A)" "(DC)" "(R)" "(C)" ## [481] "(C)" "(A)" "(M)" "(C)" "(C)" ## [486] "(S)" "(S)" "(S)" "(A)" "(R)" ## [491] "(M)" "(A)" "(R)" "(A)" "(A)" ## [496] "(R)" "(R)" "(R)" "(S)" "(C)" ## [501] "(C)" "(S)" "(A)" "(S)" "(M)" ## [506] "(M)" "(S)" "(A)" "(A)" "(S)" ## [511] "(A)" "(C)" "(DC)" "(S)" "(S)" ## [516] NA "(A)" NA "(R)" "(C)" ## [521] "(S)" "(C)" "(S)" "(A)" "(A)" ## [526] "(A)" "(A)" "(C)" "(A)" "(A)" ## [531] "(A)" "(A)" "(C) (NSW)" "(A)" "(C)" ## [536] "(R)" "(S)" "(A)" "(R)" "(C)" ## [541] "(A)" "(S)" "(A)" "(A)" ``` -- <div class="info-box" style="position:absolute;right:20px;margin-right:0px!important;bottom:50px;margin-left:0;width:900px;font-size: 20pt;"> <ul> <li>What is <code>"\\(.+\\)"</code>???</li> {{content}} </ul> </div> -- <li>This is a pattern expressed as <b>regular expression</b> or <b>regex</b> for short</li> {{content}} -- <li>Note in R, you have to add an extra <code>\</code> when <code>\</code> is included in the pattern <span class="font_small">(yes this means that you can have a lot of backslashes... just keep adding <code>\</code> until it works! Enjoy <a href="https://xkcd.com/1638/">this xkcd comic</a>.)</span></li> {{content}} -- <li>From R v4.0.0 onwards, you can use raw string to elimiate all the extra <code>\</code>, e.g. <code>r"(<span class="monash-blue">\(.+\)</span><code>)"</code> is the same as <code class="monash-blue">"\\(.+\\)"</code></li> --- # Regular expressions .font_small[.font_small[Part] 1] * **Regular expression**, or **regex**, is a string of characters that define a search pattern for text -- * Regular expression is... -- hard -- , but comes up often enough that it's worth learning -- ```r ozanimals <- c("koala", "kangaroo", "kookaburra", "numbat") ``` -- **.circle.bg-orange.white[=] Basic match** .grid[ .item[ ```r str_detect(ozanimals, "oo") ``` ``` ## [1] FALSE TRUE TRUE FALSE ``` ```r str_extract(ozanimals, "oo") ``` ``` ## [1] NA "oo" "oo" NA ``` ] .item[ ```r str_match(ozanimals, "oo") ``` ``` ## [,1] ## [1,] NA ## [2,] "oo" ## [3,] "oo" ## [4,] NA ``` ] ] --- # Regular expressions .font_small[.font_small[Part] 2] **.circle.bg-orange.white[=] Meta-characters** * `"."` a wildcard to match any character except a new line ```r str_starts(c("color", "colouur", "colour", "red-column"), "col...") ``` ``` ## [1] FALSE TRUE TRUE FALSE ``` -- * `"(.|.)"` a marked subexpression with alternate possibilites marked with `|` ```r str_replace(c("lovelove", "move", "stove", "drove"), "(l|dr|st)o", "ha") ``` ``` ## [1] "havelove" "move" "have" "have" ``` -- * `"[...]"` matches a single character contained in the bracket ```r str_replace_all(c("cake", "cookie", "lamington"), "[aeiou]", "_") ``` ``` ## [1] "c_k_" "c__k__" "l_m_ngt_n" ``` --- # Regular expressions .font_small[.font_small[Part] 3] **.circle.bg-orange.white[=] Meta-character quantifiers** * `"?"` zero or one occurence of preceding element ```r str_extract(c("color", "colouur", "colour", "red"), "colou?r") ``` ``` ## [1] "color" NA "colour" NA ``` -- * `"*"` zero or more occurence of preceding element ```r str_extract(c("color", "colouur", "colour", "red"), "colou*r") ``` ``` ## [1] "color" "colouur" "colour" NA ``` -- * `"+"` one or more occurence of preceding element ```r str_extract(c("color", "colouur", "colour", "red"), "colou+r") ``` ``` ## [1] NA "colouur" "colour" NA ``` --- # Regular expressions .font_small[.font_small[Part] 4] * `"{n}"` preceding element is matched exactly `n` times ```r str_replace(c("banana", "bananana", "bana", "banananana"), "ba(na){2}", "-") ``` ``` ## [1] "-" "-na" "bana" "-nana" ``` -- * `"{min,}"` preceding element is matched `min` times or more ```r str_replace(c("banana", "bananana", "bana", "banananana"), "ba(na){2,}", "-") ``` ``` ## [1] "-" "-" "bana" "-" ``` -- * `"{min,max}"` preceding element is matched at least `min` times but no more than `max` times ```r str_replace(c("banana", "bananana", "bana", "banananana"), "ba(na){1,2}", "-") ``` ``` ## [1] "-" "-na" "-" "-nana" ``` --- # Regular expressions .font_small[.font_small[Part] 5] **.circle.bg-orange.white[=] Character classes** * `[:alpha:]` or `[A-Za-z]` to match alphabetic characters * `[:alnum:]` or `[A-Za-z0-9]` to match alphanumeric characters * `[:digit:]` or `[0-9]` or `\\d` to match a digit * `[^0-9]` to match non-digits * `[a-c]` to match a, b or c * `[A-Z]` to match uppercase letters * `[a-z]` to match lowercase letters * `[:space:]` or `[ \t\r\n\v\f]` to match whitespace characters * and more... --- # View matches with regular expressions .grid-row[ .item[ ```r str_view(c("banana", "bananana", "bana", "banabanana"), "ba(na){1,2}") ``` <div id="htmlwidget-d7bf9d5f00de1038a409" style="width:960px;height:100%;" class="str_view html-widget"></div> <script type="application/json" data-for="htmlwidget-d7bf9d5f00de1038a409">{"x":{"html":"<ul>\n <li><span class='match'>banana<\/span><\/li>\n <li><span class='match'>banana<\/span>na<\/li>\n <li><span class='match'>bana<\/span><\/li>\n <li><span class='match'>bana<\/span>banana<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script> ] .item[ ```r str_view_all(c("banana", "bananana", "bana", "banabanana"), "ba(na){1,2}") ``` <div id="htmlwidget-fa0dda4e801849e08249" style="width:960px;height:100%;" class="str_view html-widget"></div> <script type="application/json" data-for="htmlwidget-fa0dda4e801849e08249">{"x":{"html":"<ul>\n <li><span class='match'>banana<\/span><\/li>\n <li><span class='match'>banana<\/span>na<\/li>\n <li><span class='match'>bana<\/span><\/li>\n <li><span class='match'>bana<\/span><span class='match'>banana<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script> ] ] --- count: false # View matches with regular expressions .grid-row[ .item[ ```r str_view(c("banana", "bananana", "bana", "banabanana"), "ba(na){1,2}") ``` <div id="htmlwidget-d826aba0061cc689530c" style="width:960px;height:100%;" class="str_view html-widget"></div> <script type="application/json" data-for="htmlwidget-d826aba0061cc689530c">{"x":{"html":"<ul>\n <li><span class='match'>banana<\/span><\/li>\n <li><span class='match'>banana<\/span>na<\/li>\n <li><span class='match'>bana<\/span><\/li>\n <li><span class='match'>bana<\/span>banana<\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script> ] .item[ ```r str_view_all(c("banana", "bananana", "bana", "banabanana"), "ba(na){1,2}") ``` <div id="htmlwidget-b0e94cb89293e6148452" style="width:960px;height:100%;" class="str_view html-widget"></div> <script type="application/json" data-for="htmlwidget-b0e94cb89293e6148452">{"x":{"html":"<ul>\n <li><span class='match'>banana<\/span><\/li>\n <li><span class='match'>banana<\/span>na<\/li>\n <li><span class='match'>bana<\/span><\/li>\n <li><span class='match'>bana<\/span><span class='match'>banana<\/span><\/li>\n<\/ul>"},"evals":[],"jsHooks":[]}</script> ] ] <div class="info-box" style="position:absolute;right:20px;margin-right:0px!important;top:100px;margin-left:0;width:900px;font-size: 20pt;"> <ul> <li>When a function in <code>stringr</code> ends with <code>_all</code>, all matches of the pattern are considered</li> <li>The one <i>without</i> <code>_all</code> only considers the first match</li> </ul> </div> --- # .font_small[Back to] Extracting the string ```r str_extract(LGA, "\\(.+\\)") ``` ``` ## [1] "(C)" "(S)" "(R)" "(S)" "(R)" ## [6] "(S)" "(DC)" "(R)" "(DC)" "(C)" ## [11] "(DC)" "(S)" "(S)" "(S)" "(DC)" ## [16] "(A)" "(C)" "(A)" "(T)" "(RC)" ## [21] "(A)" "(S)" "(S)" "(S)" "(C)" ## [26] "(DC)" "(R)" "(A)" "(C)" "(DC)" ## [31] "(S)" "(S)" "(A)" "(S)" "(S)" ## [36] "(R)" "(M)" "(A)" "(C)" "(S)" ## [41] "(S)" "(C)" "(A)" "(S)" "(C)" ## [46] "(AC)" "(A)" "(S)" "(A)" "(C)" ## [51] "(A)" "(R)" "(S)" "(T)" "(C)" ## [56] "(S)" "(S)" "(R)" "(C)" "(T)" ## [61] "(C)" "(S)" "(C)" "(C)" "(C)" ## [66] "(C)" "(S)" "(DC)" "(DC)" "(S)" ## [71] "(R)" "(R)" "(S)" "(B)" "(DC)" ## [76] "(M)" "(A)" "(C)" "(S)" "(S)" ## [81] "(S)" "(S)" "(S)" "(S)" "(S)" ## [86] "(C)" "(A)" "(C)" "(A)" "(S)" ## [91] "(C)" "(A)" "(S)" "(S)" "(S)" ## [96] "(S)" "(DC)" "(S)" "(S)" "(S)" ## [101] "(C)" "(C)" "(DC)" "(S)" "(S)" ## [106] "(C)" "(S)" "(DC)" "(C)" "(C)" ## [111] "(S)" "(S)" "(S)" "(S)" "(S)" ## [116] "(S)" "(A)" "(DC)" "(S)" "(A)" ## [121] "(C)" "(A)" "(S)" "(A)" "(DC)" ## [126] "(S)" "(C)" "(S)" "(A)" "(S)" ## [131] "(M)" "(S)" "(DC)" "(R)" "(C)" ## [136] "(C)" "(S)" "(C)" "(S)" "(T)" ## [141] "(S)" "(S)" "(DC)" "(S)" "(T)" ## [146] "(C)" "(S)" "(M)" "(S)" "(DC)" ## [151] "(C)" "(S)" "(M)" "(C)" "(S)" ## [156] "(C)" "(C)" "(R)" "(S)" "(C)" ## [161] "(C)" "(R)" "(S)" "(C)" "(A)" ## [166] "(T)" "(S)" "(RC)" "(C)" "(A)" ## [171] "(A)" "(A)" "(S)" "(A)" "(S)" ## [176] "(S)" "(T)" "(S)" "(S)" "(S)" ## [181] "(A)" "(DC)" "(M)" "(C)" "(S)" ## [186] "(A)" "(T)" "(A)" "(C)" "(S)" ## [191] "(C)" "(R)" "(C)" "(S)" "(S)" ## [196] "(S)" "(S)" "(R)" "(C)" "(DC)" ## [201] "(A)" "(DC)" "(R)" "(C)" "(S)" ## [206] "(S)" "(C)" "(C)" "(R)" "(S)" ## [211] "(S)" "(C)" "(A)" "(S)" "(S)" ## [216] "(C)" "(DC)" "(S)" "(M) (Tas.)" "(M) (Tas.)" ## [221] "(C) (Vic.)" "(C) (Vic.)" "(S)" "(DC)" "(S)" ## [226] "(RC)" "(S)" "(DC)" "(S)" "(S)" ## [231] "(R)" "(S)" "(A)" "(C)" "(C)" ## [236] "(A)" "(A)" "(RC)" "(S)" "(C)" ## [241] "(S)" "(S)" "(S)" "(C)" "(C)" ## [246] "(S)" "(C)" "(C)" "(C)" "(A)" ## [251] "(C)" "(S)" "(S)" "(S)" "(S)" ## [256] "(S)" "(A)" "(A)" "(A)" "(S)" ## [261] "(A)" "(A)" "(S)" "(S)" "(C)" ## [266] "(A)" "(M)" "(S)" "(S)" "(C)" ## [271] "(R)" "(S)" "(R)" "(DC)" "(R)" ## [276] "(C)" "(S)" "(S)" "(C)" "(S)" ## [281] "(A)" "(R)" "(DC)" "(A)" "(C)" ## [286] "(A)" "(S)" "(S)" "(A)" "(C)" ## [291] "(C)" "(A)" "(T)" "(S)" "(C)" ## [296] "(A)" "(A)" "(S)" "(S)" "(T)" ## [301] "(C)" "(A)" "(A)" "(DC)" "(A)" ## [306] "(C)" "(M)" "(M)" "(S)" "(A)" ## [311] "(A)" "(C)" "(C)" "(S)" "(DC)" ## [316] "(S)" "(C)" "(S)" "(S)" "(DC)" ## [321] "(RegC)" "(C)" "(S)" "(S)" NA ## [326] "(A)" "(S)" "(A)" "(S)" "(A)" ## [331] "(S)" "(C)" "(R)" "(C)" "(S)" ## [336] "(A)" "(DC)" "(S)" "(A)" "(R)" ## [341] "(S)" "(S)" "(RC)" "(T)" "(A)" ## [346] "(M)" "(A)" "(S)" "(S)" "(S)" ## [351] "(S)" "(A)" "(RC)" "(S)" "(A)" ## [356] "(R)" "(S)" "(S)" "(C)" "(S)" ## [361] "(DC)" "(M)" "(M)" "(AC)" "(DC)" ## [366] "(A)" "(A)" "(S)" "(S)" "(A)" ## [371] "(C)" "(S)" "(S)" "(C)" "(R)" ## [376] "(S)" "(S)" NA "(A)" "(T)" ## [381] "(S)" "(A)" "(C)" "(C)" "(A)" ## [386] "(C)" "(DC)" "(C)" "(A)" "(A)" ## [391] "(A)" "(S)" "(DC)" "(DC)" "(S)" ## [396] "(M)" "(R)" "(DC)" "(C)" "(S)" ## [401] "(S)" "(C)" "(C)" "(C)" "(C)" ## [406] "(C)" "(S)" "(A)" NA "(S)" ## [411] "(C)" "(S)" "(M)" "(C)" "(S)" ## [416] "(S)" NA "(C)" "(S)" "(C)" ## [421] "(DC)" "(S)" "(C)" "(S)" "(C)" ## [426] "(M)" "(A)" "(A)" "(A)" "(S)" ## [431] "(C)" "(S)" "(S)" "(S)" "(A)" ## [436] "(A)" "(A)" "(S)" "(S)" "(S)" ## [441] "(C)" "(S)" "(C)" "(C)" "(C)" ## [446] "(C) (NSW)" "(S) (Qld)" "(R) (Qld)" "(DC) (SA)" "(C) (SA)" ## [451] "(M) (Tas.)" "(M) (Tas.)" "(C)" "(R)" "(M)" ## [456] "(C)" "(R)" "(S)" "(RC)" "(S)" ## [461] "(M)" "(C)" "(R)" "(C)" "(DC)" ## [466] "(C)" "(C)" "(M)" "(C)" "(S)" ## [471] "(C)" "(DC)" "(M)" "(S)" "(C)" ## [476] "(C)" "(A)" "(DC)" "(R)" "(C)" ## [481] "(C)" "(A)" "(M)" "(C)" "(C)" ## [486] "(S)" "(S)" "(S)" "(A)" "(R)" ## [491] "(M)" "(A)" "(R)" "(A)" "(A)" ## [496] "(R)" "(R)" "(R)" "(S)" "(C)" ## [501] "(C)" "(S)" "(A)" "(S)" "(M)" ## [506] "(M)" "(S)" "(A)" "(A)" "(S)" ## [511] "(A)" "(C)" "(DC)" "(S)" "(S)" ## [516] NA "(A)" NA "(R)" "(C)" ## [521] "(S)" "(C)" "(S)" "(A)" "(A)" ## [526] "(A)" "(A)" "(C)" "(A)" "(A)" ## [531] "(A)" "(A)" "(C) (NSW)" "(A)" "(C)" ## [536] "(R)" "(S)" "(A)" "(R)" "(C)" ## [541] "(A)" "(S)" "(A)" "(A)" ``` --- count: false # .font_small[Back to] Extracting the string ```r str_extract(LGA, "\\(.+\\)") %>% table() ``` ``` ## . ## (A) (AC) (B) (C) (C) (NSW) (C) (SA) (C) (Vic.) ## 100 2 1 120 2 1 2 ## (DC) (DC) (SA) (M) (M) (Tas.) (R) (R) (Qld) (RC) ## 40 1 23 4 38 1 7 ## (RegC) (S) (S) (Qld) (T) ## 1 182 1 12 ``` -- <blockquote> Where the same Local Government Area name appears in different States or Territories, the State or Territory abbreviation appears in parenthesis after the name. Local Government Area names are therefore unique.<br> <a href="https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/1270.0.55.003~June%202020~Main%20Features~Local%20Government%20Areas%20(LGAs)~3" style="float:right">-Australian Bureau of Statistics</a> </blockquote> --- # .font_small[Retry] Extracting the string ```r str_extract(LGA, "\\([^)]+\\)") %>% table() ``` ``` ## . ## (A) (AC) (B) (C) (DC) (M) (R) (RC) (RegC) (S) (T) ## 100 2 1 125 41 27 39 7 1 183 12 ``` --- count: false # .font_small[Retry] Extracting the string ```r str_extract(LGA, "\\([^)]+\\)") %>% # remove the brackets str_replace_all("[\\(\\)]", "") %>% table() ``` ``` ## . ## A AC B C DC M R RC RegC S T ## 100 2 1 125 41 27 39 7 1 183 12 ``` * `"[]"` for single character match * We want to match `(` and `)` but these are meta-characters * So we need to escape it to have it as a literal: `\(` and `\)` * But we must escape the escape character... so it's actually `\\(` `\\)` --- # .font_small[R v4.0.0] Extracting the string <pre> <code class="r hljs remark-code"> <div class="remark-code-line">str_extract(LGA, <span style="background-color:yellow">r<span class="hljs-string">"(</span></span><span class="hljs-string">\([^)]+\)<span style="background-color:yellow">)"</span></span>) %&gt;% </div> <div class="remark-code-line"> <span class="hljs-comment"># remove the brackets</span></div> <div class="remark-code-line"> str_replace_all(<span style="background-color:yellow">r<span class="hljs-string">"(</span></span><span class="hljs-string">[\(\)]<span style="background-color:yellow">)"</span></span>, <span class="hljs-string">""</span>) %&gt;% </div> <div class="remark-code-line"> table()</div> </code> </pre> <pre> <code class="r hljs remark-code"><div class="remark-code-line"><span class="hljs-comment">## .</span></div> <div class="remark-code-line"><span class="hljs-comment">## A AC B C DC M R RC RegC S T </span></div> <div class="remark-code-line"><span class="hljs-comment">## 100 2 1 125 41 27 39 7 1 183 12</span></div> </code> </pre> * If using R v4.0.0 onwards, you can use the raw string version instead --- class: transition Regex still difficult? {{content}} <img src="https://raw.githubusercontent.com/gadenbuie/regexplain/af4fe0988a10f34dc528b4d359b80bb06af7809a/docs/regexplain-selection.gif"> -- Try RStudio addin <code class="yellow">regexplain</code> --- # `RVerbalExpressions` * If you still find it difficult, you may find an expressive piping approach to be easier for you: ```r library(RVerbalExpressions) ``` ``` ## Warning: package 'RVerbalExpressions' was built under R version 4.0.2 ``` ```r rx_start_of_line() %>% rx_find('http') %>% rx_maybe('s') %>% rx_find('://') %>% rx_maybe('www.') %>% rx_anything_but(' ') %>% rx_end_of_line() ``` ``` ## [1] "^(http)(s)?(\\://)(www\\.)?([^ ]*)$" ``` .font_small[I don't use this but it sure is easier to understand!] .footnote[ Tyler Littlefield (2019). RVerbalExpressions: Create Regular Expressions Easily. R package version 0.1.0 ] --- # `stringr::str_glue` or `glue::glue` ```r animal <- c("koala", "kangaroo", "numbat") quality <- c("cuddly", "cool", "cute") paste0("I love ", animal, ", it's so ", quality, "!") ``` ``` ## [1] "I love koala, it's so cuddly!" "I love kangaroo, it's so cool!" ## [3] "I love numbat, it's so cute!" ``` * It works, but we have to break out of the string constantly to refer to variables in the environment -- , but `str_glue` saves you the trouble! ```r str_glue("I love {animal}, it's so {quality}!") ``` ``` ## I love koala, it's so cuddly! ## I love kangaroo, it's so cool! ## I love numbat, it's so cute! ``` .footnote[ Jim Hester (2020). glue: Interpreted String Literals. R package version 1.4.2. ] -- <div class="info-box pad20" style="position:absolute;bottom:20px;right:10px;margin-right:0px;width:300px;"> <code>str_glue</code> is just a wrapper for <code>glue</code> from the <code>glue</code> package </div> --- # `stringr::str_glue_data` or `glue::glue_data` ```r df <- data.frame(animal = animal, quality = quality) glue::glue_data(df, "I love {animal}, it's so {quality}!") ``` ``` ## I love koala, it's so cuddly! ## I love kangaroo, it's so cool! ## I love numbat, it's so cute! ``` ```r stringr::str_glue_data(df, "I love {animal}, it's so {quality}!") ``` ``` ## I love koala, it's so cuddly! ## I love kangaroo, it's so cool! ## I love numbat, it's so cute! ``` --- class: exercise middle hide-slide-number # <i class="fas fa-code"></i> If you installed the `dwexercise` package, <br> run below in your R console ```r learnr::run_tutorial("day1-exercise-03", package = "dwexercise") ``` <br> # <i class="fas fa-link"></i> If the above doesn't work for you, go [here](https://ebsmonash.shinyapps.io/dw-day1-exercise-03). # <i class="fas fa-question"></i> Questions or issues, let us know! <center> <div class="countdown clock" id="timer_5fc4c8fb" style="right:0;bottom:0;" data-warnwhen="0"> <code class="countdown-time"><span class="countdown-digits minutes">15</span><span class="countdown-digits colon">:</span><span class="countdown-digits seconds">00</span></code> </div> </center> --- class: font_smaller background-color: #e5e5e5 # Session Information .scroll-350[ ```r devtools::session_info() ``` ``` ## 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