How to Split Strings in Python With the split() Method

Key Takeaways

hello everyone welcome to our second video in the series on splitting concatenating and joining strings in Python this video will focus on the string methods split split creates a list of sub strings from the string instance that invoked it before we get started let's review two things from the previous video first strings are immutable sequences meaning they can't be changed this property is key to understanding string methods in general string methods can't modify the string instance they're invoked upon therefore the string methods we discuss here we'll all be creating new values or objects second although string methods can be invoked as static methods directly from the string class this is not recommended going forward we will explore our string methods by invoking them the usual way from their string object instance now let's talk about split here we see an example of the split method the job of split is to create sub strings based on the position of a separator character or string within the string instance split then returns a list object with those sub strings as elements the separator used to delimit these string portions depends on what if any character or string was passed as an argument since this argument is used in this way only strings can be passed as the separator there are no restrictions however on the type of character or length of string that serves this purpose the split method can be invoked without passing any arguments if nothing is passed split uses whitespace as its default separator as you can see invoking split from our sentence string effectively creates a list of words with this default behavior split can be helpful in generating a word count on large blocks of text once a split is called on the text block Len can be used to count the elements in the returned list sometimes however we don't want split to use white space as our string delimiter for example say we wanted to break apart our sentence string at the lowercase s we simply pass the lowercase s as a string argument to split split we'll then use that character as a separator to generate the list elements which you can see from this result note also that the separator character the S is missing from the sub strings that were generated so how could this be useful you may have seen data in a format known as CSV or comma separated values here's an example of the United States zip code data in this format split can be useful in reading CSV data because we can specify the comma character as our split delimiter thereby identifying the field values within each record or row since split uses white space as its default separator you might assume that explicitly passing a space character string argument would function the same but there is a slight difference this difference is apparent in the returned list when working upon a stream with leading or trailing whitespace in this situation passing a literal space character to split produces empty strings in the list result another useful feature of split involves the use of its optional second parameter max split the default value of back split is negative 1 which means it has no real effect however if a positive integer has passed us the max split argument that number will be the maximum number of times a split will use the separator for example if a 1 is specified from xsplit the split methods job is complete after the first separator position is found the remaining separators will then be ignored so how might max split be useful if we revisit our zip code CSV example let's suppose we want to treat the city and state as one field value called location without specifying the max split argument a split on the comma character would render a three string list however specifying the integer one for max split would stop splitting after the first comma the one following the zip code now split returns a two string list where we can treat our city and state as one field here you see the comma after the city is now part of the string in the second element hopefully this video showed how split can be useful and perhaps you can use split in some of your own applications now that we've broken our strings of parts let's put them back together again in the next video