Python is a general-purpose high-level programming language. Python is mainly used as a support language to software developers. It helps in building control and management and also in testing. The syntax python uses is very simple and similar to the English language. In python, because of its syntax, it allows developers to write the same code in fewer lines as compared to many other languages. Unlike HTML, CSS, and JavaScript, Python can be used for general-purpose programming and software development besides web development.
The latest Python version available for download is Python 3.9.1.
Advantages of Python
Python is a versatile and very easy to use language, and is also fast to develop. The advantages of python language over other programming languages are:-
Easy to read and learn
Python is a programming language that uses the English language like syntax. This makes it much easier to understand the code. Learning python language isn’t as difficult as other major languages like C++ or Java for the very same reason. Python is also very much recommended for beginners to start their coding journey.
Productivity
Due to the simplicity of syntax, the programmer can focus more on the problem statement rather than trying to understand and figure out the syntax, hence improving productivity. To solve the same problem in any other language requires more lines of code as compared to python, hence, again increasing productivity; write less and work more.
Interpreted Language and Dynamically Typed
Python is an interpreted language, meaning that the code gets executed line by line, and in case of any error, it stops further execution and reports back the error. This makes the process of resolving any errors or debugging much easier and faster.
Another advantage of the Python programming language is that it is dynamic. This means that unless we execute the code, the variable datatype remains unknown. The assignment of the data type to the variable is automatic upon execution of the code. This frees the programmer from the hassle of assigning data types and also keeping them in mind while writing the rest of the code.
Support Libraries
Python has a huge and vast standard library where most functions can be found. This makes coding in python very easy without too much hassle of importing a library for every function.
Interaction with other modules
The PyPI or Python Package Index makes it possible for Python to interact with other platforms and languages using third-party modules. The pip or Python Package Manager makes it possible to import any package from the PyPI. The PyPI consists of over 200,000 packages.
Data Structures
Python has extremely user-friendly data structures. The built-in list and dictionary data structures help construct fast runtime data structures. The dynamic high-level data typing helps keep the supporting code simple and short, which could be used in case of any need.
Portability
Unlike languages like C/C++ where you have to change the code at times to run it on different platforms, python requires no such changes in its code. The code written once can be run on any platform, anywhere. Only one important thing to remember is, no system-dependent features should be included.
Disadvantages of python
There are always two sides to a coin. Python has multiple advantages over other programming languages, but it has its disadvantages as well. While python is maybe easier to code in and to understand and may have a wide range of applications, python is not suitable for Mobile and Game Development. The disadvantages of python are:-
Speed
Although python is a high-level language, it is very slow. The line-by-line execution is the cause of its slow execution. Another reason for its slow execution is that it is dynamic in nature.
Memory
Python uses large amounts of memory instead of memory optimization. Again, due to its dynamic nature, it consumes lots of memory and is not the best choice for any memory-intensive task.
Mobile application development
Due to being mostly a server-side programming language, it isn’t suitable for the development of mobile applications. Compared to other languages, Python has slow processing power and is not very memory efficient, hence it is not any programmer’s first choice for mobile application development.
Database access
The python database is considered a little underdeveloped and primitive. Although python is very easy and stress-free, its database access pulls it one step back since most big enterprises require the smooth running of the interaction of complex legacy data.
Runtime errors
Even though being dynamic is a huge advantage, many times it could lead to a huge disadvantage: Runtime errors. Python requires more amount of testing and time, and some variable previously holding an integer value is later given a string value causing the runtime errors.
What is Python Regular Expression?
Regular Expressions (also known as Rational expressions) are a special sequence of character which are useful in searching for a match in strings or a set of characters. These expressions use special syntax which is kept in a pattern that later helps in searching for the string.
Python also provides functions, like every other programming language, which are helpful in various ways. These functions are predefined in the language and can be called anywhere in the program. To call any regular expression in python, we use () after the name of the function. The regular expression generally uses 11 meta characters. To import the built-in package for the regular expression:
import reBasic functions of the Python Regular Expression
The built-in package of the Python Regular Expression or the re module has a set of defined functions which allow the user to search a string for a match. These functions are:
- findall: Returns a list containing all matches found.
- search: Returns a match object if there is a match anywhere in the string. A Match Object is an object containing all the information about the search and also the result. In case of no match, the value “none” will be returned.
- split: Returns a list where the string has been split at each match.
- sub: Replaces one or many matched with a string.
Let us consider an example to search for a string of 4 letters starting with ‘a’ and ending with ‘e’.
To specify regular expressions, we use meta characters. ^ and $ are the meta characters in the above table.
To write the above table in the form of a code:
import re
check = '^a..e$'
testString = 'abyss'
result = re.match(check, testString)
if result:
print("Search successful")
else:
print("Search unsuccessful") MetaCharacters
Meta characters are simply characters with a meaning. They are interpreted in a special way by a RegEx engine. The meta characters are:-
[] – Square brackets
The square brackets specify a set of characters that you would want to match. Consider the table below:
The above table shows the search result for the meta character [].
[ijk] will match if the string you are trying to match contains any of the letters i, j, or k. In case there are multiple letters that you want to check for which are in a sequence, it can be written using a hyphen in the square bracket. Numbers can also be checked and written in the same manner. For example,- [i-m] is the same as [ijklm].
- [5-9] means the same as [56789].
- [2-56] is the same as [23456].
Another method to represent a many letters, sequential or not is using the invert ^ function. This will search for all letters except the ones mentioned in the square bracket.
- [^jklde] means any character except j, k, l, d, and e.
- [^457] indicates any character except the numbers 4, 5, and 7.
- [^0-9] means that any non-digit character.
. – Period
The meta character Period matches any single character. This does not include the new line or /n character. Consider the following table –
As it can be observed from the table above, the first word has a total of 4 characters, and since we have given ‘…’, the output obtained is 1 match, meaning 3 characters are available. Similarly, in the second word, there are 6 characters, hence the output is 2 matches. In the third word, since there are only 2 characters, it says no match. The fourth word contains 10 characters, hence there are 3 matches.
^ – Caret
The meta character Caret checks if the word starts with a specific character. Consider the table below –
From the table above, we can notice that in case 1 of ^k, the first 2 examples give a match while the third one doesn’t. Similarly, in case 2 of ^ki, the first example gives 2 matches since 2 words start with ‘ki’, while the second example does not give a match since the first k is not followed by i.
$ – Dollar
The meta character $ checks if a string ends with a certain character. It is very similar to meta character caret. Consider the table below –
The table above shows an example to check if the last letter of the word is t.
* – Star
The meta character * checks for zero or more occurrences.
The string dopn is not matched since the o is not followed by n.
+ – Plus
The meta character + is almost the same as the *, but here it checks for one or more occurrences.
The output for the first example dn is obtained as no match since there is no ‘o’ character existing. Similar to the previous case of *, the string dopn is not matched since the o is not followed by n.
? – Question Mark
The meta character ? is again very similar to both * and +, but matches zero or one occurrence of the pattern only.
The third string here gives the output as No match because there is more than one ‘o’ in the string. As for the fourth string, the reason stays sane as the * and the +.
{} – Braces
Just like the previous three meta characters, this also checks the occurrence, but this checks exactly the specified number of occurrences in the braces. Consider the example below –
From the above table, we can observe that the criteria for a match is the repetition of the character ‘i’ either/and 3 or 4 times. In case 1, the occurrence of ‘i’ is once and twice in the two strings, hence the output is no match. Similarly, in case 2, the occurrence of ‘i’ is once and thrice in the two strings respectively, hence the output is one match. Similarly for the case 3 and 4 as well.
| – Alternation
The meta character | works like the normal OR operator. It gives a match if any of the characters in the expression are present irrespective of each other.
From the above table, we observe that any string with the letter ‘d’ and/or ‘e’ gives a match. If the string does not contain the characters ‘d’ or ‘e’, then the result is no match.
() – Group
The meta character () finds its use in grouping sub-patterns. Consider the following table –
The above table shows the example where the output is a match if and only if ‘i’ or/and ‘j’ or/and ‘k’ is compulsorily followed by ‘ab’.
Summary
Python is very versatile and easy to use language. Python makes coding fun and easy for beginners as well as professionals because it uses lesser lines of code to perform the same function that would take too many lines in any other language. It also uses an English-like syntax making it easier to understand. Python Regular Expression is a very handy and important tool which can be used to find certain characters in a whole set of string using metacharacters.
