Remove Strings Found in Vector 1, from Vector 2

Remove strings found in vector 1, from vector 2

Try this,

sample1 <- c(".aaa", ".aarp", ".abb", ".abbott", ".abogado")
sample2 <- c("try1.aarp", "www.tryagain.aaa", "255.255.255.255", "onemoretry.abb.abogado")
paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b")
# [1] "(\\.aaa|\\.aarp|\\.abb|\\.abbott|\\.abogado)\\b"
gsub(paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b"), "", sample2)
# [1] "try1"            "www.tryagain"    "255.255.255.255" "onemoretry" 

Explanation:

• sub("\\.", "\\\\.", sample1) escapes all the dots. Since dots are special chars in regex.

• paste(sub("\\.", "\\\\.", sample1), collapse="|") combines all the elements with | as delimiter.

• paste0("(",paste(sub("\\.", "\\\\.", sample1), collapse="|"),")\\b") creates a regex like all the elements present inside a capturing group followed by a word boundary. \\b is a much needed one here . So that it would do an exact word match.

Comparing 2 vectors and removing elements from 2nd vector that are not found in the 1st - c++

If you are not allowed to sort the vectors then you can use the following approach as it is shown in the demonstrative program below.

#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>

int main() 
{
    std::vector <std::string> animals = 
    {
        "cat", "dog", "pig", "tiger", "monkey", "lion"
    };

    std::vector <std::string> someAnimals = 
    {
        "dog", "mouse", "snake", "monkey", "cat"
    };

    auto not_present = [&animals]( const auto &s )
    {
        return 
        std::find( std::begin( animals ), std::end( animals ), s ) == std::end( animals );
    };

    someAnimals.erase( std::remove_if( std::begin( someAnimals ),
                                       std::end( someAnimals ),
                                       not_present ), std::end( someAnimals ) );

    for ( const auto &s : someAnimals )
    {
        std::cout << s << ' ';
    }
    std::cout << '\n';

    return 0;
}

The program output is

dog monkey cat 

Otherwise you can use std::binary_search for the sorted vectors as shown below.

#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>

int main() 
{
    std::vector <std::string> animals = 
    {
        "cat", "dog", "pig", "tiger", "monkey", "lion"
    };

    std::vector <std::string> someAnimals = 
    {
        "dog", "mouse", "snake", "monkey", "cat"
    };

    std::sort( std::begin( animals ), std::end( animals ) );
    std::sort( std::begin( someAnimals ), std::end( someAnimals ) );

    auto not_present = [&animals]( const auto &s )
    {
        return 
        not std::binary_search( std::begin( animals ), std::end( animals ), s );
    };

    someAnimals.erase( std::remove_if( std::begin( someAnimals ),
                                       std::end( someAnimals ),
                                       not_present ), std::end( someAnimals ) );

    for ( const auto &s : someAnimals )
    {
        std::cout << s << ' ';
    }
    std::cout << '\n';

    return 0;
}

remove element by position in a vector string in c++

[Note: With the assumption 1003;2021-03-09;False;0;0;1678721F corresponding to a row inside std::vector<string>]

---

std::remove : Removes from the vector either a single element (position) or a range of elements ([first, last)).

In case std::vector<string> plan contains value False then it is removed.

  std::vector < std::string > plan =
  {
     "1003","2021-03-09","False","0;0","1678721F"
      
  };
  
  std::remove(plan.begin(),plan.end(),"False");

---

In your case you need to remove given sub-string from each row of the plan. You need to iterate through all the rows to remove given value using std::string::erase.

  std::vector < std::string > plan =
  {
     "1003;2021-03-09;False;0;0;1678721F",
      "1005;2021-03-05;False;0;0;1592221D",
      "1005;2021-03-06;False;0;0;1592221D",
      "1003;2021-03-07;False;0;0;1592221D",
      "1003;2021-03-08;False;0;0;1592221D",
      "1004;2021-03-09;False;0;0;1592221D",
      "1004;2021-03-10;False;0;0;1592221D",
      "1001;2021-03-11;False;0;0;1592221D"};

    for (auto & e:plan)
    {
      //As position of False;0;0; is at a fixed index, i.e: from index:16, 10 characters are removed
      e.erase (16, 10);
    }

---

To generalize, You can make use of std::String::find to find a sub-string and erase it.

void removeSubstrs(string& s, string p) { 
  string::size_type n = p.length();
  for (string::size_type i = s.find(p);
      i != string::npos;
      i = s.find(p))
      s.erase(i, n);
}

int
main ()
{

  std::vector < std::string > plan =
  {
     "1003;2021-03-09;False;0;0;1678721F",
      "1005;2021-03-05;False;0;0;1592221D",
      "1005;2021-03-06;False;0;0;1592221D",
      "1003;2021-03-07;False;0;0;1592221D",
      "1003;2021-03-08;False;0;0;1592221D",
      "1004;2021-03-09;False;0;0;1592221D",
      "1004;2021-03-10;False;0;0;1592221D",
      "1001;2021-03-11;False;0;0;1592221D"};

    for (auto & e:plan)
    {
      removeSubstrs (e, ";False;0;0");
    }
    
    for (auto e:plan)
        std::cout << e << std::endl;

  return 0;
}

how may I remove elements in a string vector by elements in another string vector

setdiff is asymmetric, as the help page warns about (though subtly).

This works as you expect,

> setdiff(c("a","b","c","d"),c("a","c"))
[1] "b" "d"

A simple function works either way,

setdiff2 <- function(x,y){
  d1 <- setdiff(x,y)
  d2 <- setdiff(y,x)
  if(length(d2) > length(d1))
    return(d2)
  else
    return(d1)
}

> setdiff2(c("a","c"), c("a","b","c","d"))
[1] "b" "d"

Removing strings from a string vector, from a substring

Use std::remove_if and search for a 1 in the string (live example):

clauses.erase(
    std::remove_if(clauses.begin(), clauses.end(), 
        [](const std::string &s) {return s.find('1') != std::string::npos;} 
    ), 
    clauses.end()
);

If you don't have C++11 for the lambda, a normal function, or functor, or Boost lambda, or whatever floats your boat, will work as well.

Remove entries from string vector containing specific characters in R

We can use grep to find out which values in y match the pattern in x and exclude them using !%in%

y[!y %in% grep(paste0(x, collapse = "|"), y, value = T)]

#[1] "kot" "kk"  "y"  

Or even better with grepl as it returns boolean vectors

y[!grepl(paste0(x, collapse = "|"), y)]

---

A concise version with grep using invert and value parameter

grep(paste0(x, collapse = "|"), y, invert = TRUE, value = TRUE)
#[1] "kot" "kk"  "y"  

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