PymateIO-mapping

Abstract

The map() function is very popular and useful function in Arduino world.

Pymate includes the maps.py library regrouping interpolation, categorization and other functions sourced from MC Hobby libraries.

map() function

The map() function is used to perform linear interpolation along the line identified by two points (start and stop).

The maps() results is floating point value. It can be casted to integer with int(maps( ... )).

def map(value, istart, istop, ostart, ostop):

Function parameters:

• value : The input value (integer or float) within the range istart..istop.
• istart : minimal value of input range (integer or float).
• istop : maximal value of the input range (integer or float).
• ostart : minimal value of output range (integer or float).
• ostop : maximal value of the output range (integer or float).

Function results:

The function will returns the output value (a float) in the range ostart..ostop. It is the resulting value corresponding to the input value .

ranking() function

The ranking() function is used to categorize an input value within a limited set of ranges.

The function can also transpose the categorized value with a list of output values (when defined in the call).

def ranking( value, ranges, transposed=None ):

Function parameters:

• value : the input value compared to the various ranges. When falling into a range, the resulting output value is the lower value of the range (or corresponding transposed value when defined). None is return when the input value is below the very first range.
• ranges : list of increasing values defining the n ranges. Ranges can be read as follows range[0]..range[1], range[1]..range[2], range[2]..range[3], ... range[n-1]..range[n]
• transposed : (optional) list of transposed value for each entry of the ranges list. When defined, the resulting output (lower value of the range) is replaced with the corresponding entry from the transposed list.

Function results:

The lower value of the range within the input value falls otherwise `None` when the input value do not fit any range. The resulting value can be replace with its `transposed` equivalent (when `transposed` is defined).

Example 1

from maps import ranking

result = ranking( val, [10,20,30,40] )

• will returns None for val < 10
• will returns 10 for val>= 10 and val < 20
• will returns 20 for val>= 20 and val < 30
• will returns 30 for val>= 30 and val < 40
• will returns 40 for val>= 40

Example 2

from maps import ranking

result = ranking( val, [10,20,30,40], ["A", "B", "C", "D"] )

• will returns None for val < 10
• will returns "A" for val>= 10 and val < 20
• will returns "B" for val>= 20 and val < 30
• will returns "C" for val>= 30 and val < 40
• will returns "D" for val>= 40

slice_by() function

It exists situation where you need to split a long list into smaller sub-lists of a given length.

It is the purpose of the slice_by() function creating a list of sub-list each having N items.

def slice_by( lst, by_len ):

Function parameters:

• lst : the source list.
• by_len : the split length of the sub-lists.

Example 1

from maps import slice_by

l = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]
print( "slice by 5", slice_by(l,5) )

which prints the following

slice by 5 [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], 
[11, 12, 13, 14, 15], [16, 17, 18, 19, 20], 
[21, 22, 23, 24, 25], [26]]