String-range class.

This class provides functions to convert a string representing integers and ranges of integers to an object which can be iterated over all the values contained in the string and a list of individual values or subranges can be retrieved.

EXAMPLE::

>>> sr = srange("1,3,4-5,8-11,12-13,20")
>>> for val in sr:
                        print("%d," % val),
1, 3, 4, 5, 8, 9, 10, 11, 12, 13, 20,

NOTE:

String ranges can only contain integer numbers and must be strictly monotonically increasing. Multiple identical values are not allowed. addition of __resort_list() now allows for mis-ordered simple ranges, but they still must not overlap.

TODO:

The issues of the above note should be addressed to make the code more robust and forgiving. There is no reason one should not specify sub- ranges in arbitrary orders.

The range is checked to be monotonic, it returns None if no more values last is the last number obtained from this range, use -Inf to get start of range, it returns the next

variables and methods that you may be interested in

after(val)[source]¶

Return the value or the element that follows after the given value.

EXAMPLE::

>>> sr = srange("3,5,9-20")
>>> print sr.after(5)
9

first()[source]¶

Return the number of the first item in the range. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> sr = srange("3,5,9-20")
>>> print sr.first()
3

index(n)[source]¶

Return the n-th element from the string range. This method uses but does not change any internal variables, e.g. no self.xxxx

is_in_range(item)[source]¶

Return True if item is in string range self.r, False otherwise. This method uses but does not change any internal variables, e.g. no self.xxxx

last()[source]¶

Return the value of the last item in the range. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> sr = srange("3,5,9-20")
>>> print sr.last()
20

len()[source]¶

Return the number of items in the string range. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> sr = srange("3,5,9-20")
>>> print sr.len()
14

list()[source]¶

Expand a string range into a standard python list. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> print srange("3,5,9-13").list()
[3, 5, 9, 10, 11, 12, 13]

CAUTION:

The following statement:

>>> list("1-100000",";")

will produce a list with 100000 elements!

Max list length for a 32 bit system is (2^32 - 1)/2/4 = 536870912 on my computer I get a MemoryError for lengths > 1e8, so limit to 1e7

next()[source]¶

Return the next value in the string range. Also update self.previous_item.

reset_previous()[source]¶

Reset previous_item to the lowest possible integer value.

sub_range(start, n, set_last=False)[source]¶

Return a sub range from the original range as a new range string.

The new range starts at with the value start and has up to n elements. If start is not an element in the range, then it begin with first element after start. If set_last is True, then self.previous_item is set to the new end, otherwise no change is made. This method only changes an internal variable “self.previous_item” when set_last is True.

EXAMPLE::

>>> sr = srange('3,5,9-20')
>>> print sr.sub_range(start = 5, n = 3)
5,9-10

val2index(val)[source]¶

Return the index into the srange that corresponds to val. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> r = '3, 5, 9-20'
>>> print val2index(5)
1

symrange class.

This class provides functions to loop symmetrically outward from 0 i.e., 0,1,-1,2,-2,3,-3,... endVal can only be a positive integer or 0

EXAMPLE::

>>> for i in symrange(2): print i
prints:
0 1 -1 2 -2 3 -3

>>> for i in symrange(2,True): print i
prints:
0 -1 1 -2 2 -3 3

NOTE:

symrange can only contain integers.

variables and methods that you may be interested in:

after(val)[source]¶

Return the value of the element that follows after val (which is given).

first()[source]¶

Return the value of the first item in the range. This is just for completeness, it always returns 0

index(n)[source]¶

Returns the n-th element from the range, zero based, n==0 is first element. This method uses but does not change any internal variables, e.g. no self.xxxx This functionality also available by symrange(2)[n], which calles __getitem__() below

last()[source]¶

Return the value of the last item in the range. This method uses but does not change any internal variables, e.g. no self.xxxx

len()[source]¶

Return the number of items in the symrange. Usage: as symrange(3).len()

list()[source]¶

Expands the symrange into a standard python list. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> print symrange(2).list()
[0, 1, -1, 2, -2]

CAUTION:

The following statement:

>>> symrange(100000).list()

will produce a list with 200001 elements!

Max list length for a 32 bit system is (2^32 - 1)/2/4 = 536870912 on my computer I get a MemoryError for lengths > 1e8, so limit to 1e7

next()[source]¶

Return the next value in the symrange.

val2index(val)[source]¶

Return the index into the symrange that produces val. This method uses but does not change any internal variables, e.g. no self.xxxx

EXAMPLE::

>>> sr = symrange(4)
>>> print sr.val2index(3)
5