String formatting in Python

Question

I want to do something like String.Format("[{0}, {1}, {2}]", 1, 2, 3) which returns:

[1, 2, 3]

How do I do this in Python?

Answer 1

The previous answers have used % formatting, which is being phased out in Python 3.0+. Assuming you're using Python 2.6+, a more future-proof formatting system is described here:

http://docs.python.org/library/string.html#formatstrings

Although there are more advanced features as well, the simplest form ends up looking very close to what you wrote:

>>> "[{0}, {1}, {2}]".format(1, 2, 3)
[1, 2, 3]

Answer 2

You can do it three ways:

---

Use Python's automatic pretty printing:

print [1, 2, 3]   # Prints [1, 2, 3]

Showing the same thing with a variable:

numberList = [1, 2]
numberList.append(3)
print numberList   # Prints [1, 2, 3]

---

Use 'classic' string substitutions (ala C's printf). Note the different meanings here of % as the string-format specifier, and the % to apply the list (actually a tuple) to the formatting string. (And note the % is used as the modulo(remainder) operator for arithmetic expressions.)

print "[%i, %i, %i]" % (1, 2, 3)

Note if we use our pre-defined variable, we'll need to turn it into a tuple to do this:

print "[%i, %i, %i]" % tuple(numberList)

---

Use Python 3 string formatting. This is still available in earlier versions (from 2.6), but is the 'new' way of doing it in Py 3. Note you can either use positional (ordinal) arguments, or named arguments (for the heck of it I've put them in reverse order.

print "[{0}, {1}, {2}]".format(1, 2, 3)

Note the names 'one' ,'two' and 'three' can be whatever makes sense.)

print "[{one}, {two}, {three}]".format(three=3, two=2, one=1)

Answer 3

You're looking for string formatting, which in python is based on the sprintf function in C.

print "[%s, %s, %s]" % (1, 2, 3)

For a complete reference look here: http://docs.python.org/library/stdtypes.html#string-formatting

Answer 4

PEP 498 which landed in python 3.6 added literal string interpolation, which is basically a shortened form of format.

You can now do:

f"[{1}, {2}, {3}]"

Common other uses I find useful are:

pi = 3.141592653589793
today = datetime(year=2018, month=2, day=3)

num_2 = 2     # Drop assigned values in
num_3 = "3"   # Call repr(), or it's shortened form !r
padding = 5   # Control prefix padding
precision = 3 #   and precision for printing


f"""[{1},
     {num_2},
     {num_3!r},
     {pi:{padding}.{precision}},
     {today:%B %d, %Y}]"""

Which will produce:

"[1,\n     2,\n     '3',\n      3.14,\n     February 03, 2018]"

Answer 5

To print elements sequentially use {} without specifying the index

print('[{},{},{}]'.format(1,2,3))

(works since python 2.7 and python 3.1)

Answer 6

I think that this combination is missing :P

"[{0}, {1}, {2}]".format(*[1, 2, 3])

Answer 7

You haven't formulated yourself very commendably, but I'll venture a guess this is what you're looking for:

foo = "Hello"
bar = "world"
baz = 2
print "%s, %s number %d" % (foo, bar, baz)

Answer 8

You have lot of solutions :)

simple way (C-style):

print("[%i, %i, %i]" %(1, 2, 3))

Use str.format()

print("[{0}, {1}, {2}]", 1, 2, 3)

Use str.Template()

s = Template('[$a, $b, $c]')
print(s.substitute(a = 1, b = 2, c = 3))

You can read PEP 3101 -- Advanced String Formatting

Answer 9

Very short answer.

example: print("{:05.2f}".format(2.5163)) returns 02.51

• {} Set here Variable
• : Start Styling
• 0 leading with zeroes, " " leading with whitespaces
• 5 LENGTH OF FULL STRING (Point counts, 00.00 is len 5 not 4)
• .2 two digit after point, with rounding.
• f for floats

Answer 10

Before answering this question please go through couple of articles given below:

Python Official Docs here

Useful article:

• Python String format() - here

Now let's answer this question

Question: I want to do something like:

String.Format("[{0}, {1}, {2}]", 1, 2, 3) which returns:

[1, 2, 3]

How do I do this in Python?

Answer:

Well this is certainly a one-line code answer which is

print("[{0},{1},{2}]".format(1, 2, 3))

When you execute this one-line code a list containing three values as [1, 2, 3] will be printed. I hope this was pretty simple and self-explanatory.

Thanks

Tanu

Answer 11

Since python-3.6, Python supports literal string interpolation ^[pep-498]. You thus can format with an f prefix to the string. For example:

x = 1
y = 2
z = 3
f'[{x}, {y}, {z}]'

This then produces:

>>> f'[{x}, {y}, {z}]'
'[1, 2, 3]'

In C# (the language of the String.Format(…)) in the question, since c#-6.0, string interpolation ^{[microsoft-doc]} is supported as well, for example:

int x = 1;
int y = 2;
int z = 3;
string result = $"[{x}, {y}, {z}]";

For example:

csharp> int x = 1;
csharp> int y = 2;
csharp> int z = 3;
csharp> $"[{x}, {y}, {z}]";
"[1, 2, 3]"

Answer 12

If you don't know how many items are in list, this aproach is the most universal

>>> '[{0}]'.format(', '.join([str(i) for i in [1,2,3]]))

'[1, 2, 3]'

It is mouch simplier for list of strings

>>> '[{0}]'.format(', '.join(['a','b','c']))
'[a, b, c]'

Answer 13

There are 3 ways.

"%" operator which is the original way:

x, y, z = 1, 2, 3

print("[%i, %i, %i]" % (x, y, z)) # [1, 2, 3]

"str.format()" since Python 2.6:

x, y, z = 1, 2, 3

print("[{0}, {1}, {2}]".format(x, y, z)) # [1, 2, 3]

"f-strings" since Python 3.6:

x, y, z = 1, 2, 3

print(f'[{x}, {y}, {z}]') # [1, 2, 3]

Answer 14

There are several places where you can get answers, for example here and here.

There are lots of ways of formatting a string in python, like:

1. Using the format() function, for example:

x = 'hello'
y = 'person'
xy = '{} {}'.format(x, y)

2. Using f-strings, for example:

x = 'hello'
y = 'person'
xy = f'{x} {y}'