Python str to raw

Python Raw Strings

In this article, we will see how to take care of a backslash combined with certain alphabet forms literal characters which can change the entire meaning of the string using Python. Here, we will see the various ways to use the string text as it is without its meaning getting changed.

When to use raw strings in Python ?

Raw strings are particularly useful when working with regular expressions, as they allow you to specify patterns that may contain backslashes without having to escape them. They are also useful when working with file paths, as they allow you to specify paths that contain backslashes without having to escape them. Raw strings can also be useful when working with strings that contain characters that are difficult to type or read, such as newline characters or tabs. In general, raw strings are useful anytime you need to specify a string that contains characters that have special meaning in Python, such as backslashes, and you want to specify those characters literally without having to escape them.

str = r'Python\nis\easy\to\learn' Output: Python\nis\easy\to\learn Explanation: As we can see that the string is printed as raw, and it neglected all newline sign(\n) or tab space (\t).

Count occurrences of escape sequence in string

In this example, we will find the length of the string by using the Python len() function. Then, we replace backslash ( \ ) with double backslashes ( \\ ) in the string and now find the length of the update string. Later, we find the difference between the lengths of the updated string and the original string to calculate the count of escape sequences in the string.

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Convert String to Raw String in Python

Raw strings provide a useful way to describe strings in Python so that the backslashes and their succeeding characters are not interpreted as escape sequences. The interpreter does not implement the escape sequence in such strings but rather considers them as normal characters.

This tutorial will demonstrate how to convert string to raw string in Python.

Convert String to Raw String in Python

Strings are immutable objects which means that we cannot modify them. In the methods discussed below, converting string to raw string indicates that we will create a raw string from the existing string.

Using the r Prefix to Convert String to Raw String in Python

As discussed earlier, raw strings are just a different way to describe strings in Python. We can create such raw strings by adding the prefix r before the string declaration.

This is the syntax that conveys to the Python interpreter to create a raw string.

Using the repr() Function to Convert String to Raw String in Python

The repr() function is used to return the actual string representation of a given object. It is similar to the str() function, but the str() function returns the printable string representation.

We can use it to convert string to raw string in Python.

Using the encode() and decode() Functions to Convert String to Raw String in Python

Python 3 treats a string as a collection of Unicode characters. We can use the encode() function is used to encode the string to the specified encoding and similarly the decode() function decodes the encoded string.

We can use these functions one after the other to convert string to raw string in Python. First, we will encode the string to the unicode_escape encoding which will ensure that the backslashes are not escaped, and then decode it to preserve the escape sequences like a raw string.

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Convert a string into a raw string (Python recipe) by Brett Cannon

This function takes in an arbitrary string and converts it into its raw string equivalent. Unfortunately \x will raise a ValueError and I cannot figure out how to deal with it.

[2001-06-18: Completely reworked function for performance]

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escape_dict='\a':r'\a', '\b':r'\b', '\c':r'\c', '\f':r'\f', '\n':r'\n', '\r':r'\r', '\t':r'\t', '\v':r'\v', '\'':r'\'', '\"':r'\"', '\0':r'\0', '\1':r'\1', '\2':r'\2', '\3':r'\3', '\4':r'\4', '\5':r'\5', '\6':r'\6', '\7':r'\7', '\8':r'\8', '\9':r'\9'> def raw(text): """Returns a raw string representation of text""" new_string='' for char in text: try: new_string+=escape_dict[char] except KeyError: new_string+=char return new_string 

This is very useful for when a user needs to input text and you want the raw equivalent to be used and not the processed version. A good example of this situation is when a user passes in a regex from some place like the command line.

Its main limitation is that it does not deal with all octal escape characters. If anyone has any suggestions on how to handle them without resorting to typing out every octal escape character then please respond to this recipe with the solution.

This function can be (and was originally) implemented as a huge if/elif/else. It can also have escape_dict contain all possible printable characters (thanks to string.printable[:-5]) and thus not have to deal with the try/except. But numbers don’t lie and profiling all three different ways put this version as the fastest one.

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Необработанная строка в Python

Необработанная строка в Python создается путем добавления к строковому литералу префикса «r» или «R». Необработанная строка Python рассматривает обратную косую черту (\), как буквальный символ. Это полезно, когда мы хотим иметь строку, содержащую обратную косую черту, и не хотим, чтобы она рассматривалась как escape-символ.

Допустим, мы хотим создать строку Hi\nHello в python. Если мы попытаемся назначить его обычной строке, \n будет рассматриваться как новая строка.

Давайте посмотрим, как необработанная строка помогает нам рассматривать обратную косую черту как нормальный символ.

raw_s = r'Hi\nHello' print(raw_s)

Давайте посмотрим на другой пример, где символ, за которым следует обратная косая черта, не имеет особого значения.

>>> s = 'Hi\xHello' File "", line 1 SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \xXX escape

Мы получили ошибку, потому что python не знает, как декодировать ‘\ x’, поскольку он не имеет особого значения. Давайте посмотрим, как мы можем создать ту же строку, используя необработанные строки.

>>> s = r'Hi\xHello' >>> print(s) Hi\xHello

Не путайте с выводом с двумя обратными косыми чертами. Это просто для того, чтобы показать это как обычную строку Python с экранированием обратной косой черты.

Когда за обратной косой чертой следует кавычка в необработанной строке, она экранируется. Однако обратная косая черта также остается в результате. Из-за этой функции мы не можем создать необработанную строку с одиночной обратной косой чертой. Кроме того, необработанная строка не может иметь нечетное количество обратных косых черт в конце.

Некоторые из недопустимых необработанных строк:

r'\' # missing end quote because the end quote is being escaped r'ab\\\' # first two backslashes will escape each other, the third one will try to escape the end quote.

Давайте посмотрим на некоторые допустимые примеры необработанных строк в кавычках.

raw_s = r'\'' print(raw_s) raw_s = r'ab\\' print(raw_s) raw_s = R'\\\"' # prefix can be 'R' or 'r' print(raw_s)

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How To Use Python Raw String

You can create a raw string in Python by prefixing a string literal with r or R . Python raw string treats the backslash character (\) as a literal character. Raw string is useful when a string needs to contain a backslash, such as for a regular expression or Windows directory path, and you don’t want it to be treated as an escape character. This article covers the basics of how Python raw strings work and provides a few common examples of how to use raw strings to include special characters in strings.

The examples in this article use the Python interactive console in the command line to demonstrate different raw string scenarios.

Including a Newline Character in a String Using Raw String

This example uses a string with a value: Hi\nHello . If you try to assign this value to a normal string, then the newline character ( \n ) creates a new line:

The output shows that the newline character results in a new line.

To include the newline character in the string, prefix the string variable with r or R to create a raw string:

The output includes the newline character.

Including Double Backslash Characters in a String Using Raw String

If you try to include double backslash characters, such as for a hostname path, in a normal string, then the first backslash character won’t print because the compiler considers the backslash to be an escape indicator.

For example, create a string that contains a path:

\examplehost\digitalocean\content\ 

The output shows that the first backslash character isn’t included in the string.

To include both backslash characters in the string, prefix the string variable with r or R to create a raw string:

\\examplehost\digitalocean\content\ 

The output includes both backslash characters.

Troubleshooting Quotes and Backslash Characters in Raw Strings

In a raw string, quotes can still be escaped with a single backslash character, however, the backslash character remains in the resulting raw string.

In addition, a raw string can’t end with an odd number of backslash characters. Because of this feature, you can’t create a raw string that contains a single backslash character, so r»/» is an invalid string.

Invalid Raw String Examples

In this example, the end quote is missing from the output since it’s being escaped by the backslash character resulting in an unterminated string literal error:

In this example, the first two backslashes will escape each other, and the third one will try to escape the end quote, resulting in an unterminated string literal error:

Valid Raw String Examples

Here are some examples of valid raw strings that include quotes and backslash characters.

Create a raw string that escapes quotes:

The output shows that the backslash characters escape the quotes so that the string doesn’t terminate, but the backslash characters remain in the result string.

Create a raw string with an even number of backslash characters:

The output shows that the even number of backslash characters are included in the result string.

Conclusion

In this article, you learned the basics of raw strings in Python. Continue your learning about Python strings.

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