Python_crib_notes-Lit_string.md

String

< Back

---

• str()
• Quoting and manipulation examples
• Formatting
  • 'hi {} from {}'.format(x,y)
  • 'hi {b} from {a}'.format(a=" ",b=" ")
  • sprintf style - 'The value of x is %3.2f' %12.3456789
• Handy-dandy _to_low_camel_case function

---

str()

strings = "This is Python"
char = "C"
multiline_str = """This is a multiline string with more than
one line code."""
unicode = u"\u00dcnic\u00f6de"
raw_str = r"raw \n string"

print(strings)
print(char)
print(multiline_str)
print(unicode)
print(raw_str)

This is Python
C
This is a multiline string with more than
one line code.
Ünicöde
raw \n string

Quoting and manipulation examples

print("Strings separated by white space "
    'are concatenated.' ''' Including triple quoted,
    which may have embedded line returns and whitespace.''')
# Strings separated by white space are concatenated. Including triple quoted,
#    which may have embedded line returns  and whitespace.

print("Concatenation usefully splits "
    "long strings onto multiple lines.")
# Concatenation usefully splits long string literals onto multiple lines.

print("""\
The backslash above usefully makes the content all on the same line
""")
# The backslash above usefully makes the content all on the same line

print(3 * "I'm tripled " + ", and I'm concatenated.")
# I'm tripled I'm tripled I'm tripled , and I'm concatenated.

this_string_variable = 'This string variable'
print( this_string_variable + " (and some Built-in functions) be concatented with this string literal.")
# This string variable (and some Built-in functions) be concatented with this string literal.

word = 'Py'
word += 'thon'    # 'Python' Concatenation, then re-assignment, NOT string mutation
print(word[0])    # 'P' 1st character
print(word[2])    # '3' 6th character
print(word[-1])   # 'n' last character
print(word[-2])   # 'o' 2nd-last character
print(word[-6])   # 'P' 1st character
print(word[0:2])  # 'Py'characters from position 0 (included) to 2 (excluded)
print(word[::2])  # 'Pto' every second character
print(word[2:99]) # 'thon' out of range slice indexes are handled gracefully
print(len(word))  # '6' String length

# These all invalid;
# word[99]        - IndexError: string index out of range
# word[0] = 'J'   - Strings immutability ->
#                   TypeError: 'str' object does not support item assignment

print( f"{word}'s f-string") # 'Python's f-string'

Formatting

'hi {} from {}'.format(x,y)

'hi {b} from {a}'.format(a=" ",b=" ")

sprintf style - 'The value of x is %3.2f' %12.3456789

Handy-dandy _to_low_camel_case function

• This is a useful function I've needed a few times.
• Automatically converts strings if the parts are broken up by any non-alphanumeric characters like "_", " ", "-" . Eg. FLOOD_LIGHT_CONFIG would become floodLightConfig.
• By default only converts if some non-alphanumeric delimiters are present to prevent something like floodLightConfig becoming floodlightconfig

def _to_lower_camel_case(string: str, delimiters_required = True) -> str:
    from re import split

    if delimiters_required and string.isalnum():
        # String doesn't contain any delimiters to identify words, so skip conversion
        return string

    return "".join(
        part.lower() if i == 0 else part.title()
        for i, part in enumerate(split("([^a-zA-Z0-9])", string))
        if part.isalnum()
    )
``