One common operation is to map values from one range (say, 5 to 10), to another range (say, -35 to 120). For this, map functions are provided.
Map functions included in the music library, so, in order to use them, you need the following in your program:
from music import *
Map functions are used to expand, contract, or offset data values. They convert a numeric value from one range to another.
For example, mapping the value 0 from the range 0..100 to the range 10..20 results in 10:
>>> mapValue(0, 0, 100, 10, 20) 10
Notice how 0 is the leftmost value in its range, as is 10.
Similarly, mapping 50 from the range 0..100 to the range 10..20 results in 15:
>>> mapValue(50, 0, 100, 10, 20) 15
Again, notice how 50 is in the middle of its range, and so is 15.
So, map functions maintain the relative position of a value.
NOTE: If you use float numbers, mapValue() will return a float value that is properly scaled (preserving accuracy):
>>> mapValue(49 , 0, 100, 10, 20) 14 >>> mapValue(49 , 0, 100, 10.0, 20.0) 14.9
Notice how in the second example, 49 was mapped to 14.9, since the destination range was float.
| Function | Description |
| mapValue(value, minValue, maxValue, minResult, maxResult) | Takes a number within one range and returns its equivalent within another range. The arguments are:
|
| mapScale(value, minValue, maxValue, minResult, maxResult, scale, key) | Takes a number (i.e., MIDI pitch) within one range and returns a its equivalent within another range, quantized to the pitch class value in scale. The arguments are:
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Making Music with Computers 