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...range of numbers is desired, Python provides the range builtin function, which creates a list of numbers. The range function takes three arguments, start, end and step. start and step are optional, and default to 0 and 1, respectively. The range function creates a list of numbers, starting at start, with a step of step, up to, but not including end, so that range(10) produces a list that has exactly 10 items, the numbers 0 through 9. Using the range function, the above example would look like ...
...range(range(10)) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> range(range(5), range(10)) [5, 6, 7, 8, 9] >>> range(range(5), range(10), range(2)) [5, 7, 9] >>> list(xrange(range(10))) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> list(xrange(xrange(10))) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] # Number the lines of a file: lines = file.readlines() for num in range(lines): print num, lines[num] Alternatives A natural alternative to the above specification is allowing xrange() to acc...
...Range; void PyLineTable_InitAddressRange(char *linetable, Py_ssize_t length, int firstlineno, PyCodeAddressRange *range); int PyLineTable_NextAddressRange(PyCodeAddressRange *range); int PyLineTable_PreviousAddressRange(PyCodeAddressRange *range); PyLineTable_InitAddressRange initializes the PyCodeAddressRange struct from the line number table and first line number. PyLineTable_NextAddressRange advances the range to the next entry, returning non-zero if valid. PyLineTable_PreviousAddressRange ...
...range() format needed fixing, "The whole point (15 years ago) of range() was to avoid needing syntax to specify a loop over numbers. I think it's worked out well and there's nothing that needs to be fixed (except range() needs to become an iterator, which it will in Python 3.0)." Rationale One of the most common uses of for-loops in Python is to iterate over an interval of integers. Python provides functions range() and xrange() to generate lists and iterators for such intervals, which work b...
...range(100) if n*n < 50) which is equivalent to the using a generator function (PEP 255): def __gen(exp): for n in exp: if n*n < 50: yield n g = __gen(iter(range(10))) would yield 0, 1, 2, 3, 4, 5, 6 and 7, but would also consider the numbers from 8 to 99 and reject them all since n*n >= 50 for numbers in that range. Allowing for a "while" clause would allow the redundant tests to be short-circuited: g = (n for n in range(100) while n*n < 50) would also y...
...range() or xrange() function to generate a sequence of indices as in, for example: for rowcount in range(table.getRowCount()): print table.getValueAt(rowcount, 0) or for rowcount in xrange(table.getRowCount()): print table.getValueAt(rowcount, 0) From time to time there are discussions in the Python community about the indexed for-loop idiom. It is sometimes argued that the need for using the range() or xrange() function for this design idiom is: Not obvious (to new-to-Python progr...
...range(1, n+1): for i in range(1, n+1): print i, 'x', j, '=', i*j print Now suppose the second exercise is to add printing to a different file. With the new syntax, the programmer only needs to learn one new thing: print >> file, and the answer can be like this: def tables(n, file=sys.stdout): for j in range(1, n+1): for i in range(1, n+1): print >> file, i, 'x', j, '=', i*j print >> file With only a print statement...
...range, and this motivated using ranges to highlight syntax errors, which was very well received. Additionally, it has been noted that users with vision problems can identify the ranges much easily than a single caret character, which we believe is a great advantage of using ranges. Have a configure flag to opt out Having a configure flag to opt out of the overhead even when executing Python in non-optimized mode may sound desirable, but it may cause problems when reading pyc files that were ...
...ranges = [range(i) for i in range(5)] >>> [*item for item in ranges] [0, 0, 1, 0, 1, 2, 0, 1, 2, 3] >>> {*item for item in ranges} {0, 1, 2, 3} This was met with a mix of strong concerns about readability and mild support. In order not to disadvantage the less controversial aspects of the PEP, this was not accepted with the rest of the proposal. Unbracketed comprehensions in function calls, such as f(x for x in it), are already valid. These could be extended to: f(*x for x ...
...range(4)]) is semantically equivalent to: >>> {i : chr(65+i) for i in range(4)} The dictionary constructor approach has two distinct disadvantages from the proposed syntax though. First, it isn't as legible as a dict comprehension. Second, it forces the programmer to create an in-core list object first, which could be expensive. Examples >>> print {i : chr(65+i) for i in range(4)} {0 : 'A', 1 : 'B', 2 : 'C', 3 : 'D'} >>> print {k : v for k, v in someDict.iter...
...range This solution adds two built-in functions indices and irange. The semantics of these can be described as follows: def indices(sequence): return range(len(sequence)) def irange(sequence): return zip(range(len(sequence)), sequence) These functions could be implemented either eagerly or lazily and should be easy to extend in order to accept more than one sequence argument. The use of these functions would simplify the idioms for looping over the indices and over both elements and i...
...range(10)) but you would have to write: reduce(operator.add, (x**2 for x in range(10))) and also: g = (x**2 for x in range(10)) i.e. if a function call has a single positional argument, it can be a generator expression without extra parentheses, but in all other cases you have to parenthesize it. The exact details were checked in to Grammar/Grammar version 1.49. The loop variable (if it is a simple variable or a tuple of simple variables) is not exposed to the surrounding function. This f...
...range of numeric computations so that a computation can be written once and run anywhere with at least the desired precision and range. It is backward compatible with existing code. The meaning of decimal literals is clarified. Rationale Currently it is impossible in every language except Fortran 90 to write a program in a portable way that uses floating point and gets roughly the same answer regardless of platform -- or refuses to compile if that is not possible. Python currently has only ...
...range(3) x, *unused, z = range(10) It's also used in for loops and comprehensions: for unused in range(10): ... [ SpamObject() for unused in range(10) ] The use of "_" in these cases is probably the most common, but it potentially conflicts with the use of "_" in internationalization, where a call like gettext.gettext() is bound to "_" and used to mark strings for translation. In the proposal to add Pattern Matching to Python (originally PEP 622, now split into PEP 634, PEP 635 and PEP 636), ...
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Released: June 28, 2021
This is the sixth maintenance release of Python 3.9 Note: The release you're looking at is Python 3.9.6, a bugfix release for the legacy 3.9 series. Python 3.11 is now the latest feature release series of Python 3. Get the latest release of 3.11.x here. There's been 146 commits …
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...range(), which accepts an optional parameter to the left of its required parameter. [2] dict(), whose mapping/iterator parameter is optional and semantically must be positional-only. Any externally visible name for this parameter would occlude that name going into the **kwarg keyword variadic parameter dict! [1] Obviously one can simulate any of these in pure Python code by accepting (*args, **kwargs) and parsing the arguments by hand. But this results in a disconnect between the Python funct...
...range(n) is calculated outside the timing brackets - another trick to minimize the overhead caused by the timing function. If you are worried about this overhead, you can calibrate it by calling the timing function with a do-nothing function. import time def timing(f, n, a): print f.__name__, r = range(n) t1 = time.clock() for i in r: f(a); f(a); f(a); f(a); f(a); f(a); f(a); f(a); f(a); f(a) t2 = time.clock() ...
...range L16 l 16 no full range L32 l 32 no full range LA l, a 8 no full range LA32 l, a 16 no full range RGB r, g, b 8 no full range RGB48 r, g, b 16 no full range RGBA r, g, b, a 8 no full range RGBA64 r, g, b, a 16 no full range YV12 y, cr, cb 8 1, 2, 2 16-235, 16-240, 16-240 JPEG_YV12 y, cr, cb 8 1, 2, 2 full range CMYK c, m, y, k 8 no full range CMYK64 c, m, y, k 16 no full range When the name of a mode ends with a number, it represents the average number of bits per pixel. All...
...range(3)] for j in range(2)] # I.e., a = [[0, 1, 2], [0, 1, 2]] print(TARGET) # prints 2 Translation: def f(): if False: TARGET = None def outer_genexpr(outer_iterator): nonlocal TARGET def inner_generator(inner_iterator): nonlocal TARGET for i in inner_iterator: TARGET = i yield i for j in outer_iterator: yield list(inner_generator(range(3))) a = list(outer_genexpr(range(2...
...range of books on the subject, quickly convinced them it was the right choice. The initial script development was done as a joint development between the Agency and QualiControl. The project was done in this way to help the Agency develop a solution in the shortest time possible, with simultaneous training and consulting. This resulted in a script containing over 940 standard Test&Go validation controls, enhanced with more than 5,000 lines of Python code. Total development and testing was co...