inserting characters at the start and end of a string
Strings are immutable so you can’t insert characters into an existing string. You have to create a new string. You can use string concatenation to do what you want:
Note that you can also create a string with n L s by using multiplication:
For completeness along with the other answers:
Or, more forward compatible with Python 3.x:
You can also use join:
If you want to insert other string somewhere else in existing string, you may use selection method below.
Calling character on second position:
Calling range with start and end position:
Calling part of a string before that position:
Calling part of a string after that position:
Inserting your string in 5th position.
Also s is equivalent to s[:] .
With your question you can use all your string, i.e.
or if «L» is a some other string (for example I call it as l ), then you may use that code:
string — Common string operations¶
The concatenation of the ascii_lowercase and ascii_uppercase constants described below. This value is not locale-dependent.
The lowercase letters ‘abcdefghijklmnopqrstuvwxyz’ . This value is not locale-dependent and will not change.
The uppercase letters ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ’ . This value is not locale-dependent and will not change.
The string ‘0123456789’ .
The string ‘0123456789abcdefABCDEF’ .
The string ‘01234567’ .
String of ASCII characters which are considered punctuation characters in the C locale: !"#$%&'()*+,-./:;<=>?@[\]^_`
String of ASCII characters which are considered printable. This is a combination of digits , ascii_letters , punctuation , and whitespace .
A string containing all ASCII characters that are considered whitespace. This includes the characters space, tab, linefeed, return, formfeed, and vertical tab.
Custom String Formatting¶
The built-in string class provides the ability to do complex variable substitutions and value formatting via the format() method described in PEP 3101. The Formatter class in the string module allows you to create and customize your own string formatting behaviors using the same implementation as the built-in format() method.
class string. Formatter ¶
The Formatter class has the following public methods:
The primary API method. It takes a format string and an arbitrary set of positional and keyword arguments. It is just a wrapper that calls vformat() .
Changed in version 3.7: A format string argument is now positional-only .
This function does the actual work of formatting. It is exposed as a separate function for cases where you want to pass in a predefined dictionary of arguments, rather than unpacking and repacking the dictionary as individual arguments using the *args and **kwargs syntax. vformat() does the work of breaking up the format string into character data and replacement fields. It calls the various methods described below.
In addition, the Formatter defines a number of methods that are intended to be replaced by subclasses:
Loop over the format_string and return an iterable of tuples (literal_text, field_name, format_spec, conversion). This is used by vformat() to break the string into either literal text, or replacement fields.
The values in the tuple conceptually represent a span of literal text followed by a single replacement field. If there is no literal text (which can happen if two replacement fields occur consecutively), then literal_text will be a zero-length string. If there is no replacement field, then the values of field_name, format_spec and conversion will be None .
get_field ( field_name , args , kwargs ) ¶
Given field_name as returned by parse() (see above), convert it to an object to be formatted. Returns a tuple (obj, used_key). The default version takes strings of the form defined in PEP 3101, such as “0[name]” or “label.title”. args and kwargs are as passed in to vformat() . The return value used_key has the same meaning as the key parameter to get_value() .
Retrieve a given field value. The key argument will be either an integer or a string. If it is an integer, it represents the index of the positional argument in args; if it is a string, then it represents a named argument in kwargs.
The args parameter is set to the list of positional arguments to vformat() , and the kwargs parameter is set to the dictionary of keyword arguments.
For compound field names, these functions are only called for the first component of the field name; subsequent components are handled through normal attribute and indexing operations.
So for example, the field expression ‘0.name’ would cause get_value() to be called with a key argument of 0. The name attribute will be looked up after get_value() returns by calling the built-in getattr() function.
If the index or keyword refers to an item that does not exist, then an IndexError or KeyError should be raised.
check_unused_args ( used_args , args , kwargs ) ¶
Implement checking for unused arguments if desired. The arguments to this function is the set of all argument keys that were actually referred to in the format string (integers for positional arguments, and strings for named arguments), and a reference to the args and kwargs that was passed to vformat. The set of unused args can be calculated from these parameters. check_unused_args() is assumed to raise an exception if the check fails.
format_field ( value , format_spec ) ¶
format_field() simply calls the global format() built-in. The method is provided so that subclasses can override it.
convert_field ( value , conversion ) ¶
Converts the value (returned by get_field() ) given a conversion type (as in the tuple returned by the parse() method). The default version understands ‘s’ (str), ‘r’ (repr) and ‘a’ (ascii) conversion types.
Format String Syntax¶
The str.format() method and the Formatter class share the same syntax for format strings (although in the case of Formatter , subclasses can define their own format string syntax). The syntax is related to that of formatted string literals , but it is less sophisticated and, in particular, does not support arbitrary expressions.
Format strings contain “replacement fields” surrounded by curly braces <> . Anything that is not contained in braces is considered literal text, which is copied unchanged to the output. If you need to include a brace character in the literal text, it can be escaped by doubling: << and >> .
The grammar for a replacement field is as follows:
In less formal terms, the replacement field can start with a field_name that specifies the object whose value is to be formatted and inserted into the output instead of the replacement field. The field_name is optionally followed by a conversion field, which is preceded by an exclamation point ‘!’ , and a format_spec, which is preceded by a colon ‘:’ . These specify a non-default format for the replacement value.
The field_name itself begins with an arg_name that is either a number or a keyword. If it’s a number, it refers to a positional argument, and if it’s a keyword, it refers to a named keyword argument. An arg_name is treated as a number if a call to str.isdecimal() on the string would return true. If the numerical arg_names in a format string are 0, 1, 2, … in sequence, they can all be omitted (not just some) and the numbers 0, 1, 2, … will be automatically inserted in that order. Because arg_name is not quote-delimited, it is not possible to specify arbitrary dictionary keys (e.g., the strings ’10’ or ‘:-]’ ) within a format string. The arg_name can be followed by any number of index or attribute expressions. An expression of the form ‘.name’ selects the named attribute using getattr() , while an expression of the form ‘[index]’ does an index lookup using __getitem__() .
Changed in version 3.1: The positional argument specifiers can be omitted for str.format() , so ‘<> <>‘.format(a, b) is equivalent to ‘ <0><1>‘.format(a, b) .
Changed in version 3.4: The positional argument specifiers can be omitted for Formatter .
Some simple format string examples:
The conversion field causes a type coercion before formatting. Normally, the job of formatting a value is done by the __format__() method of the value itself. However, in some cases it is desirable to force a type to be formatted as a string, overriding its own definition of formatting. By converting the value to a string before calling __format__() , the normal formatting logic is bypassed.
Three conversion flags are currently supported: ‘!s’ which calls str() on the value, ‘!r’ which calls repr() and ‘!a’ which calls ascii() .
The format_spec field contains a specification of how the value should be presented, including such details as field width, alignment, padding, decimal precision and so on. Each value type can define its own “formatting mini-language” or interpretation of the format_spec.
Most built-in types support a common formatting mini-language, which is described in the next section.
A format_spec field can also include nested replacement fields within it. These nested replacement fields may contain a field name, conversion flag and format specification, but deeper nesting is not allowed. The replacement fields within the format_spec are substituted before the format_spec string is interpreted. This allows the formatting of a value to be dynamically specified.
See the Format examples section for some examples.
Format Specification Mini-Language¶
“Format specifications” are used within replacement fields contained within a format string to define how individual values are presented (see Format String Syntax and Formatted string literals ). They can also be passed directly to the built-in format() function. Each formattable type may define how the format specification is to be interpreted.
Most built-in types implement the following options for format specifications, although some of the formatting options are only supported by the numeric types.
A general convention is that an empty format specification produces the same result as if you had called str() on the value. A non-empty format specification typically modifies the result.
The general form of a standard format specifier is:
If a valid align value is specified, it can be preceded by a fill character that can be any character and defaults to a space if omitted. It is not possible to use a literal curly brace (” < ” or “ >”) as the fill character in a formatted string literal or when using the str.format() method. However, it is possible to insert a curly brace with a nested replacement field. This limitation doesn’t affect the format() function.
The meaning of the various alignment options is as follows:
|
Option |
Meaning |
|---|---|
|
‘<‘ |
Forces the field to be left-aligned within the available space (this is the default for most objects). |
|
‘>’ |
Forces the field to be right-aligned within the available space (this is the default for numbers). |
|
‘=’ |
Forces the padding to be placed after the sign (if any) but before the digits. This is used for printing fields in the form ‘+000000120’. This alignment option is only valid for numeric types. It becomes the default for numbers when ‘0’ immediately precedes the field width. |
|
‘^’ |
Forces the field to be centered within the available space. |
Note that unless a minimum field width is defined, the field width will always be the same size as the data to fill it, so that the alignment option has no meaning in this case.
The sign option is only valid for number types, and can be one of the following:
|
Option |
Meaning |
|---|---|
|
‘+’ |
indicates that a sign should be used for both positive as well as negative numbers. |
|
‘-‘ |
indicates that a sign should be used only for negative numbers (this is the default behavior). |
|
space |
indicates that a leading space should be used on positive numbers, and a minus sign on negative numbers. |
The ‘z’ option coerces negative zero floating-point values to positive zero after rounding to the format precision. This option is only valid for floating-point presentation types.
Changed in version 3.11: Added the ‘z’ option (see also PEP 682).
The ‘#’ option causes the “alternate form” to be used for the conversion. The alternate form is defined differently for different types. This option is only valid for integer, float and complex types. For integers, when binary, octal, or hexadecimal output is used, this option adds the respective prefix ‘0b’ , ‘0o’ , ‘0x’ , or ‘0X’ to the output value. For float and complex the alternate form causes the result of the conversion to always contain a decimal-point character, even if no digits follow it. Normally, a decimal-point character appears in the result of these conversions only if a digit follows it. In addition, for ‘g’ and ‘G’ conversions, trailing zeros are not removed from the result.
The ‘,’ option signals the use of a comma for a thousands separator. For a locale aware separator, use the ‘n’ integer presentation type instead.
Changed in version 3.1: Added the ‘,’ option (see also PEP 378).
The ‘_’ option signals the use of an underscore for a thousands separator for floating point presentation types and for integer presentation type ‘d’ . For integer presentation types ‘b’ , ‘o’ , ‘x’ , and ‘X’ , underscores will be inserted every 4 digits. For other presentation types, specifying this option is an error.
Changed in version 3.6: Added the ‘_’ option (see also PEP 515).
width is a decimal integer defining the minimum total field width, including any prefixes, separators, and other formatting characters. If not specified, then the field width will be determined by the content.
When no explicit alignment is given, preceding the width field by a zero ( ‘0’ ) character enables sign-aware zero-padding for numeric types. This is equivalent to a fill character of ‘0’ with an alignment type of ‘=’ .
Changed in version 3.10: Preceding the width field by ‘0’ no longer affects the default alignment for strings.
The precision is a decimal integer indicating how many digits should be displayed after the decimal point for presentation types ‘f’ and ‘F’ , or before and after the decimal point for presentation types ‘g’ or ‘G’ . For string presentation types the field indicates the maximum field size — in other words, how many characters will be used from the field content. The precision is not allowed for integer presentation types.
Finally, the type determines how the data should be presented.
The available string presentation types are:
|
Type |
Meaning |
|---|---|
|
‘s’ |
String format. This is the default type for strings and may be omitted. |
|
None |
The same as ‘s’ . |
The available integer presentation types are:
|
Type |
Meaning |
|---|---|
|
‘b’ |
Binary format. Outputs the number in base 2. |
|
‘c’ |
Character. Converts the integer to the corresponding unicode character before printing. |
|
‘d’ |
Decimal Integer. Outputs the number in base 10. |
|
‘o’ |
Octal format. Outputs the number in base 8. |
|
‘x’ |
Hex format. Outputs the number in base 16, using lower-case letters for the digits above 9. |
|
‘X’ |
Hex format. Outputs the number in base 16, using upper-case letters for the digits above 9. In case ‘#’ is specified, the prefix ‘0x’ will be upper-cased to ‘0X’ as well. |
|
‘n’ |
Number. This is the same as ‘d’ , except that it uses the current locale setting to insert the appropriate number separator characters. |
|
None |
The same as ‘d’ . |
In addition to the above presentation types, integers can be formatted with the floating point presentation types listed below (except ‘n’ and None ). When doing so, float() is used to convert the integer to a floating point number before formatting.
The available presentation types for float and Decimal values are:
|
Type |
Meaning |
|---|---|
|
‘e’ |
Scientific notation. For a given precision p , formats the number in scientific notation with the letter ‘e’ separating the coefficient from the exponent. The coefficient has one digit before and p digits after the decimal point, for a total of p + 1 significant digits. With no precision given, uses a precision of 6 digits after the decimal point for float , and shows all coefficient digits for Decimal . If no digits follow the decimal point, the decimal point is also removed unless the # option is used. |
|
‘E’ |
Scientific notation. Same as ‘e’ except it uses an upper case ‘E’ as the separator character. |
|
‘f’ |
Fixed-point notation. For a given precision p , formats the number as a decimal number with exactly p digits following the decimal point. With no precision given, uses a precision of 6 digits after the decimal point for float , and uses a precision large enough to show all coefficient digits for Decimal . If no digits follow the decimal point, the decimal point is also removed unless the # option is used. |
|
‘F’ |
Fixed-point notation. Same as ‘f’ , but converts nan to NAN and inf to INF . |
|
‘g’ |
General format. For a given precision p >= 1 , this rounds the number to p significant digits and then formats the result in either fixed-point format or in scientific notation, depending on its magnitude. A precision of 0 is treated as equivalent to a precision of 1 . The precise rules are as follows: suppose that the result formatted with presentation type ‘e’ and precision p-1 would have exponent exp . Then, if m <= exp < p , where m is -4 for floats and -6 for Decimals , the number is formatted with presentation type ‘f’ and precision p-1-exp . Otherwise, the number is formatted with presentation type ‘e’ and precision p-1 . In both cases insignificant trailing zeros are removed from the significand, and the decimal point is also removed if there are no remaining digits following it, unless the ‘#’ option is used. With no precision given, uses a precision of 6 significant digits for float . For Decimal , the coefficient of the result is formed from the coefficient digits of the value; scientific notation is used for values smaller than 1e-6 in absolute value and values where the place value of the least significant digit is larger than 1, and fixed-point notation is used otherwise. Positive and negative infinity, positive and negative zero, and nans, are formatted as inf , -inf , 0 , -0 and nan respectively, regardless of the precision. |
|
‘G’ |
General format. Same as ‘g’ except switches to ‘E’ if the number gets too large. The representations of infinity and NaN are uppercased, too. |
|
‘n’ |
Number. This is the same as ‘g’ , except that it uses the current locale setting to insert the appropriate number separator characters. |
|
‘%’ |
Percentage. Multiplies the number by 100 and displays in fixed ( ‘f’ ) format, followed by a percent sign. |
|
None |
For float this is the same as ‘g’ , except that when fixed-point notation is used to format the result, it always includes at least one digit past the decimal point. The precision used is as large as needed to represent the given value faithfully. For Decimal , this is the same as either ‘g’ or ‘G’ depending on the value of context.capitals for the current decimal context. The overall effect is to match the output of str() as altered by the other format modifiers. |
Format examples¶
This section contains examples of the str.format() syntax and comparison with the old % -formatting.
In most of the cases the syntax is similar to the old % -formatting, with the addition of the <> and with : used instead of % . For example, ‘%03.2f’ can be translated to ‘<:03.2f>‘ .
The new format syntax also supports new and different options, shown in the following examples.
Append to a string Python + Examples
Let’s see how to append to a string python.
In this example, we will use “+” operator to append to a string in python. The code below shows appending of two string.
Example:
You can refer to the below screenshot to see the output for append to a string python.
This is how we can append to a string in Python.
Prepend to a string python
Now, we will see how to prepend to a string python.
Prepend to a string will add the element to a string. In this example, we have two strings and to get the output we will print my_string.
Example:
You can refer to the below screenshot to see the output for prepend to a string python
This is how we can prepend a string in Python.
Insert to a string python
Here, we will see how to insert to a string python.
- To insert into a string we will use indexing in python.
- Inserting into a string returns the string with another string inserted into it at a given index.
- In this example, we are inserting “New York” into “Los Angeles, Chicago” and it returns “Los Angeles, New York, Chicago”.
Example:
This is how we can insert to a sting in Python.
Append 0 to a string python
Let’s see how to append 0 to a string python.
In this example, we will use rjust function for appending 0 to a string as it offers a single line way to perform the task.
Example:
You can refer to the below screenshot to see the output for append 0 to a string python.
The above Python code we can use to append 0 to a string in Python.
Append character to a string python
Now, we will see how to append character to a string python.
- To append a character to a string we will insert the character at an index of a string and it will create a new string with that character.
- To insert a character we will use slicing a_str[:1] + “n” + a_str[1:] and the “+” operator is used to insert the desired character.
Example:
You can refer to the below screenshot to see the output for append character to a string python
This is how to append character to a string in Python.
Python append to beginning of a string in a loop
Here, we will see Python append to the beginning of a string in a loop
In this example, we will append to the beginning of a string using the for loop, and the “+” operator is used.
Example:
You can refer to the below screenshot to see the output for python add to string in a loop.
The above code, we can use to append to beginning of a string in a loop in Python.
Add letter to a string python
Here, we will see how to add letter to a string python.
To add letter to a string python we will use f”
Example:
You can refer to the below screenshot to see the output for add letter to a string python
This is python code to add letter to a string in Python.
Add variable to a string python
Let’s see how to add variable to a string python.
In this example, we will use “+” operator to add a variable to a string.
Example:
You can refer to the below screenshot to see the output for add variable to a string python
This is how to add variable to a string in Python.
Add int to a string python
Now, we will see how to add int to a string python.
Firstly, we will initialize the string and a number and by using the type conversion we will insert the number in the string, and then to get the output we will print.
Example:
You can refer to the below screenshot to see the output for add int to a string python
This is how to add int to a string in Python.
Append to end of a string in python
Here, we will see how to append to the end of a string in python
In this example, we will use the “+” operator, and to get the output we will print(string3).
Example:
You can refer to the below screenshot to see the output for append to the end of a string in python.
The above code we can use to append to end of a string in python.
How to append a new line to a string in python
Let us see how to append a new line to a string in python
In this example, to append a new line to a string we have specified the newline character by using “\n” which is also called an escape character. Hence, the string “to python” is printed in the next line.
Example:
You can refer to the below screenshot to see the output for how to append a new line to a string in python.
The above code we can use to append a new line to a string in python.
How to append backslash to a string in python
Now, we will see how to append backslash to a string in python
In this example, to append backslash to a string in python we have used the syntax “\\” to represent single backslash to a string.
Example:
You can refer to the below screenshot to see the output for how to append backslash to a string in python.
The above code we can use to append backslash to a string in python.
How to append to an empty string in python
Let’s see how to append to an empty string in python.
To append to an empty string in python we have to use “+” operator to append in a empty string.
Example:
You can refer to the below screenshot to see the output for how to append to an empty string in python.
The above code we can use to append to an empty string in python.
How to append double quotes to a string in python
Here, we will see how to append double quotes to a string in python.
To append double quotes to a string in python we have to put the string in the single quotes.
Example:
You can refer to the below screenshot to see the output for how to append double quotes to a string in python.
The above code we can use to append double quotes to a string in python.
How to append to a string in python
In python, to append a string in python we will use the ” + ” operator and it will append the variable to the existing string.
Example:
After writing the above Python code (how to append to a string in python), Ones you will print then the output will appear ” My name is Misheil and my salary is around 10000 “. Here, the ” + ” operator is used to append the variable. Also, you can refer to the below screenshot append to a string in python.
In this Python tutorial, we have learned about how to Append to a string python. Also, we covered these below topics:
- Append to a string python
- Prepend to a string python
- Insert to a string python
- Append 0 to a string python
- Append character to a string python
- Python append to the beginning of a string in a loop
- Add letter to a string python
- Add variable to a string python
- Add int to a string python
- Append to the end of a string in python
- How to append a new line to a string in python
- How to append backslash to a string in python
- How to append to an empty string in python
- How to append double quotes to a string in python
- How to append to a string in python
I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.
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статьи и идеи для разработчиков программного обеспечения и веб-разработчиков.
Заполнение строк в Python
Введение Под заполнением строки понимается добавление, как правило, неинформативных символов к строке с одного или обоих концов. Чаще всего это делается для форматирования и выравнивания вывода, но может иметь полезные практические применения. Частым случаем использования строк заполнения является вывод табличной информации в табличной форме. Вы можете сделать это разными способами, включая использование Pandas для преобразования ваших данных в настоящую таблицу. Таким образом, Python будет обрабатывать форматирование вывода на нем.
Время чтения: 7 мин.
Вступление
Заполнение строк относится к добавлению, как правило, неинформативных символов к строке на одном или обоих концах. Чаще всего это делается для форматирования и выравнивания вывода, но может иметь полезные практические применения.
Частым случаем использования строк заполнения является вывод табличной информации в табличной форме. Вы можете сделать это разными способами, включая использование Pandas для преобразования ваших данных в настоящую таблицу. Таким образом, Python будет обрабатывать форматирование вывода самостоятельно.
В этой статье мы расскажем, как дополнять строки в Python.
Скажем, у нас есть три списка:
Мы можем сформировать их в строку, используя функцию join()
Дало бы нам довольно неопрятный вывод:
Чтобы бороться с этим, мы могли бы писать for / while и добавлять пробелы к строкам до тех пор, пока они не достигнут определенной длины, и следить за тем, чтобы все данные были выровнены должным образом для облегчения визуальной проверки. Или мы могли бы использовать встроенные функции, которые могут достичь той же цели.
В этой статье мы рассмотрим следующие ljust() , center() , rjust() , zfill() и format() . Любую из этих функций можно использовать для добавления определенного количества символов к любому концу строки, включая пробелы.
Типы заполнения
Прежде чем мы более подробно рассмотрим функции, упомянутые выше, мы рассмотрим различные типы заполнения, чтобы мы могли ссылаться на них, когда говорим о функциях.
Левый отступ
Добавление левого отступа к строке означает добавление заданного символа в начало строки, чтобы сделать ее указанной длины. Левое заполнение, помимо простого форматирования и выравнивания, может быть действительно полезно при именовании файлов, которые начинаются с номера, сгенерированного в последовательности.
Например, вам нужно назвать 11 файлов, и каждый из них начинается с номера от 1 до 11. Если вы просто добавите номер в начало файла, большинство операционных систем отсортируют файлы в следующем порядке: 1 , 10 , 11 , 2 и так далее.
Это происходит, конечно, из-за правил лексикографической сортировки, но вы можете избежать этих ситуаций, называя файлы одним или несколькими ведущими нулями, в зависимости от того, сколько файлов вы ожидаете, например: 01 , 02 , 03 .
Это может быть достигнуто путем эффективного заполнения чисел слева соответствующим количеством нулей, которые сохраняют их исходное значение.
Это дает эффект выравнивания строк по левому краю.
Прокладка по центру
Это означает, что данный символ добавляется в равной мере к обеим сторонам строки, пока новая строка не достигнет заданной длины. Использование этого эффективно центрирует строку по предоставленной длине:
Это обычная строка.
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Правый отступ
Правое заполнение аналогично левому заполнению — данный символ добавляется в конец строки, пока строка не достигнет определенной длины.
Функции Python для заполнения строк
Python предлагает множество функций для форматирования и обработки строк, их использование зависит от варианта использования и личных предпочтений разработчика. Большинство функций, которые мы обсудим, имеют дело с выравниванием текста, которое, по сути, добавляет отступ к одной стороне строки. Например, чтобы строка была выровнена по левому краю , нам нужно добавить отступ в конец (с правой стороны) строки.
Примечание. Во всех функциях, которые ожидают width или len , в случае, если исходная строка длиннее указанной width или len вся строка будет сохранена без изменений. Это может иметь нежелательный эффект, когда длинные строки портят форматирование, поэтому при выборе width убедитесь, что вы указали самую длинную строку в учетной записи или в верхней границе длины.
похоть ()
Функция ljust() выравнивает строку по левому краю, добавляя правый отступ.
Функция ljust() принимает два параметра: width и fillchar . width является обязательной и определяет длину строки после добавления заполнения, а второй параметр является необязательным и представляет собой добавленный символ в исходной строке.
Значение по умолчанию — пробел , то есть ‘ ‘ . Это особенно хороший вариант для печати табличных данных, как в нашем примере в начале:
Что дает нам результат:
центр()
Функция center() выравнивает строку по центру указанной width путем равномерного добавления отступов с обеих сторон. Параметры такие же, как у функции ljust() , обязательная width и необязательный параметр fillchar
rjust ()
Аналогично двум предыдущим функциям, rjust() выравнивает строку по правому краю, добавляя отступ слева (в начале) строки.
Опять же, параметрами являются требуемая width и необязательный fillchar . Как мы упоминали ранее, эта функция очень полезна при именовании файлов, начинающихся с цифр, из-за более интуитивной сортировки:
Запуск этого кода даст нам:
zfill ()
Функция zfill() работает очень похоже на использование rjust() с нулем в качестве указанного символа. Он заполняет данную строку нулями до тех пор, пока строка не достигнет заданной длины.
Единственное отличие состоит в том, что если наша строка начинается со + ) или минус ( — ), заполнение начнется после этого знака:
Это сделано, чтобы сохранить исходное значение числа в случае, если строка была числом. Запуск этого кода даст нам:
формат()
Функция format() является самой продвинутой в списке. Эта единственная функция может использоваться для левого, правого и даже центрального отступа. Он также используется для другого форматирования , но мы рассмотрим только функции заполнения, которые он предоставляет.
Он возвращает строку после форматирования указанных значений и помещения их внутри строковых заполнителей, определенных <> .
Заполнители можно идентифицировать по именованным индексам, нумерованным индексам или даже по пустым фигурным скобкам. Быстрый пример того, как выглядят эти заполнители, прежде чем мы увидим, как мы можем использовать эту функцию для добавления отступов:
Эти заполнители допускают множество вариантов форматирования. Давайте посмотрим, как можно добиться различных типов заполнения строк, используя эти параметры:
Отступ слева: используйте > внутри заполнителя и числа, чтобы указать желаемую ширину, чтобы выровнять строку по правому краю (добавляйте символы в начале):
Отступ по центру: Аналогично, мы можем использовать ^ для отступа / выравнивания по центру:
Отступ справа: используйте < внутри заполнителей, чтобы выровнять строку по левому краю:
Вы также можете добавлять символы, отличные от пробелов, путем добавления указанных символов перед символом > , ^ или < :
Вы можете узнать больше о различных возможностях функции format() в нашем Руководстве по форматированию строк с помощью Python .
Заключение
Добавление отступов к строкам в Python — относительно простой процесс, который может заметно повысить удобочитаемость вашего вывода, особенно если данные, которые у вас есть, могут быть прочитаны в виде таблицы.
В этой статье мы рассмотрели функции ljust() , rjust() , center() , zfill() и format() как встроенные подходы к заполнению строк в Python.