Removing non-alpanumeric characters from an ordered collection of objects (list) in R

Question

I have a question about removing non-alphanumeric characters from a list in R. I have a list will all sorts of odd characters, blanks, etc. and would like to remove them. I'm generally able to remove what I want using the tm package in r. I fiddled around with it, but got nowhere so thought going back to the list may be the place to start.

The list:

 list("\n    \n", "\n\n  ", "\n        ", "               ", "\n    ", 
 "\n            \n      ", "\n        ", "Home", "\n", "Expertise", 
 "Question & Research Design", "\n", "Survey Development & Validation", 
 "\n", "Data Processing", "\n", "Statistical Analysis", "\n", 
 "Publications & Grants", "\n", "Evaluation", "\n", "\n", 
 "Consulting Areas", "Business", "\n", "Education", "K-12", 
 "\n", "Â ", " Â Â  Â  Â", " | ")

The expected output

[1] ""                               ""                         ""
[4] ""                               ""                         ""
[7] ""                               "Home"                     ""
[10] "Expertise"                     "Question Research Design" ""
[13] "Survey Development Validation" ""                         "Data Processing"
[16] ""                              "Statistical Analysis"     ""
[19] "Publications Grants"           ""                         "Evaluation"
[22] ""                              ""                         "Consulting Areas"
[25] "Business"                      ""                         "Education"
[28] "K12"                           ""                         ""
[31] ""                              ""

Answer 1

Strongly recommend you simply use

gsub("[^a-zA-Z0-9]","",x)

where x is the name of the list.

You probably included the foreign characters at the end of the list because you want these obliterating too - well, the above command achieves this. To explain briefly, the square brackets in the command define a collection of symbols, and the ^ symbol means "not", so everything that is not in the specified set of 62 characters (lower case a to z, upper case A to Z, and digits 0 to 9) will be replaced by the empty string "" (i.e. destroyed).

And here's the output...

 [1] ""                             ""                        ""
 [4] ""                             ""                        ""
 [7] ""                             "Home"                    ""
[10] "Expertise"                    "QuestionResearchDesign"  ""
[13] "SurveyDevelopmentValidation"  ""                        "DataProcessing"
[16] ""                             "StatisticalAnalysis"     ""
[19] "PublicationsGrants"           ""                        "Evaluation"
[22] ""                             ""                        "ConsultingAreas"
[25] "Business"                     ""                        "Education"
[28] "K12"                          ""                        ""
[31] ""                             ""

Answer 2

I'm not sure if this gets rid of everything you're wanting to remove... But ?regexp describes all sorts of intersting broad classes you can use. For what you're describing, I think you want:

 gsub('[[:space:]|[:punct:]]+', '', yourlist)

Which gives:

 [1] ""                            ""                            ""                            ""                           
 [5] ""                            ""                            ""                            "Home"                       
 [9] ""                            "Expertise"                   "QuestionResearchDesign"      ""                           
[13] "SurveyDevelopmentValidation" ""                            "DataProcessing"              ""                           
[17] "StatisticalAnalysis"         ""                            "PublicationsGrants"          ""                           
[21] "Evaluation"                  ""                            ""                            "ConsultingAreas"            
[25] "Business"                    ""                            "Education"                   "K12"                        
[29] ""                            "Â"                           "ÂÂÂÂ"                        ""