Gsub and sub org document

README.org

@@ -10,6 +10,10 @@ data using the R programming environment
  * [[./script/integerq_modulo.R][Integer quocient and modulo]]
  * [[./script/non_stand_eval.R][Non-standard evaluation in R]]
 
+** Matching patterns
+
+ * [[./doc/match.patt.org]['gsub' and 'sub']]
+ 
 ** Subsetting and indexing
 
  * [[./script/replace_values.R][Build column in table indexing values]]

doc/match.patt.org

@@ -0,0 +1,55 @@
+#+TITLE: Matching patterns introduction using R: grep, gsub, regex
+#+DATE: 2022-02-10
+#+AUTHOR: Jose
+#+OPTIONS: num:nil toc:2
+#+PROPERTY: header-args:R :results output :session *R1* :cmdline :tangle yes
+#+PROPERTY: header-args:R+ :exports both
+
+#+begin_src R
+  x = c(40, 30, 20, 44, 54)
+#+end_src
+
+#+RESULTS:
+
+#+begin_src R
+  y = paste0(x, "L")
+  y
+#+end_src
+
+#+RESULTS:
+: [1] "40L" "30L" "20L" "44L" "54L"
+
+** gsub function
+
+Remove the first component of each string
+
+#+begin_src R
+  gsub("^.{1}", "", y)
+#+end_src
+
+#+RESULTS:
+: [1] "0L" "0L" "0L" "4L" "4L"
+
+Remove the last component of each string
+
+#+begin_src R
+  gsub(".{1}$", "", y)
+#+end_src
+
+#+RESULTS:
+: [1] "40" "30" "20" "44" "54"
+
+#+begin_src R
+sub(".{1}$", "", y)
+#+end_src
+
+#+RESULTS:
+: [1] "40" "30" "20" "44" "54"
+
+#+begin_src R
+  noquote(y)
+#+end_src
+
+#+RESULTS:
+: [1] 40L 30L 20L 44L 54L
+