Replace Multiple Strings at Once

Replace multiple strings with multiple other strings

As an answer to:

looking for an up-to-date answer

If you are using "words" as in your current example, you might extend the answer of Ben McCormick using a non capture group and add word boundaries \b at the left and at the right to prevent partial matches.

\b(?:cathy|cat|catch)\b

\b A word boundary to prevent a partial match
(?: Non capture group
- cathy|cat|catch match one of the alternatives
) Close non capture group
\b A word boundary to prevent a partial match

Example for the original question:

let str = "I have a cat, a dog, and a goat.";
const mapObj = {
  cat: "dog",
  dog: "goat",
  goat: "cat"
};
str = str.replace(/\b(?:cat|dog|goat)\b/gi, matched => mapObj[matched]);
console.log(str);

How to replace multiple substrings of a string?

Here is a short example that should do the trick with regular expressions:

import re

rep = {"condition1": "", "condition2": "text"} # define desired replacements here

# use these three lines to do the replacement
rep = dict((re.escape(k), v) for k, v in rep.iteritems()) 
#Python 3 renamed dict.iteritems to dict.items so use rep.items() for latest versions
pattern = re.compile("|".join(rep.keys()))
text = pattern.sub(lambda m: rep[re.escape(m.group(0))], text)

For example:

>>> pattern.sub(lambda m: rep[re.escape(m.group(0))], "(condition1) and --condition2--")
'() and --text--'

Replace multiple characters in one replace call

If you want to replace multiple characters you can call the String.prototype.replace() with the replacement argument being a function that gets called for each match. All you need is an object representing the character mapping that you will use in that function.

For example, if you want a replaced with x, b with y, and c with z, you can do something like this:

const chars = {'a':'x','b':'y','c':'z'};
let s = '234abc567bbbbac';
s = s.replace(/[abc]/g, m => chars[m]);
console.log(s);

Output: 234xyz567yyyyxz

Replace multiple strings at once

You could extend the String object with your own function that does what you need (useful if there's ever missing functionality):

String.prototype.replaceArray = function(find, replace) {
  var replaceString = this;
  for (var i = 0; i < find.length; i++) {
    replaceString = replaceString.replace(find[i], replace[i]);
  }
  return replaceString;
};

For global replace you could use regex:

String.prototype.replaceArray = function(find, replace) {
  var replaceString = this;
  var regex; 
  for (var i = 0; i < find.length; i++) {
    regex = new RegExp(find[i], "g");
    replaceString = replaceString.replace(regex, replace[i]);
  }
  return replaceString;
};

To use the function it'd be similar to your PHP example:

var textarea = $(this).val();
var find = ["<", ">", "\n"];
var replace = ["<", ">", "<br/>"];
textarea = textarea.replaceArray(find, replace);

How to use str.replace to replace multiple pairs at once?

You can create a dictionary and pass it to the function replace() without needing to chain or name the function so many times.

replacers = {',':'','.':'','-':'','ltd':'limited'} #etc....
df1['CompanyA'] = df1['CompanyA'].replace(replacers)

Python: How to str.replace multiple different strings with the same replacement?

You can just use List-comprehension.

>>> [x.replace('!', '').replace('?','') for x in list_names]
['sdf', 'sdfds', 'afsafsa', 'afasf']

Also, if you have multiple strings to replace, you can even use regular expression combining them by | using re.sub function as mentioned below:

>>> import re
>>> [re.sub('\?|!', '', x) for x in list_names]
['sdf', 'sdfds', 'afsafsa', 'afasf']

Java Replacing multiple different substring in a string at once (or in the most efficient way)

If the string you are operating on is very long, or you are operating on many strings, then it could be worthwhile using a java.util.regex.Matcher (this requires time up-front to compile, so it won't be efficient if your input is very small or your search pattern changes frequently).

Below is a full example, based on a list of tokens taken from a map. (Uses StringUtils from Apache Commons Lang).

Map<String,String> tokens = new HashMap<String,String>();
tokens.put("cat", "Garfield");
tokens.put("beverage", "coffee");

String template = "%cat% really needs some %beverage%.";

// Create pattern of the format "%(cat|beverage)%"
String patternString = "%(" + StringUtils.join(tokens.keySet(), "|") + ")%";
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(template);

StringBuffer sb = new StringBuffer();
while(matcher.find()) {
    matcher.appendReplacement(sb, tokens.get(matcher.group(1)));
}
matcher.appendTail(sb);

System.out.println(sb.toString());

Once the regular expression is compiled, scanning the input string is generally very quick (although if your regular expression is complex or involves backtracking then you would still need to benchmark in order to confirm this!)

How to replace multiple strings with other multiple strings at a time in javascript?

I'd prefer to store replacements as key-value pairs in an object or as an array of pairs. Regardless of the format, you can dynamically create a regex by joining the values you want to replace using | alternation. Then give replace a callback function and use its match parameter as a key to look up its corresponding pair in the swaps object.

const s = "I am Java";const swaps = {am: "love", Java: "JS"};const pattern = new RegExp(Object.keys(swaps).join("|"), "g");console.log(s.replace(pattern, m => swaps[m]));

Replace Multiple String Elements in C#

Quicker - no. More effective - yes, if you will use the StringBuilder class. With your implementation each operation generates a copy of a string which under circumstances may impair performance. Strings are immutable objects so each operation just returns a modified copy.

If you expect this method to be actively called on multiple Strings of significant length, it might be better to "migrate" its implementation onto the StringBuilder class. With it any modification is performed directly on that instance, so you spare unnecessary copy operations.

public static class StringExtention
{
    public static string clean(this string s)
    {
        StringBuilder sb = new StringBuilder (s);

        sb.Replace("&", "and");
        sb.Replace(",", "");
        sb.Replace("  ", " ");
        sb.Replace(" ", "-");
        sb.Replace("'", "");
        sb.Replace(".", "");
        sb.Replace("eacute;", "é");

        return sb.ToString().ToLower();
    }
}