# Rounding-off spectra… [Python]

A handy little tool I knocked up last night to round-off a generated harmonic series to the nearest semi-tone (and output as a named note (C,C#,D,…) to a .txt file. Written in python, give it a root frequency, and the length of the number of partials you want to calculate.

```# Handy tool for generating a harmonic series above a given root,
# and then rounding out to the nearest 12-TET semitone.

# owmtxy, 2013
# python v.2.7.5

import math

root = input("Root frequency: ")
length = input("Spectra length: ")
freqSpectra = []
noteSpectra = []

# Write out to a .txt
file = open('harmonic_spectra_'+str(root)+'Hz.txt', 'w')

# Define note names
noteName = [
'C', 'C#', 'D', 'D#', 'E', 'F',
'F#', 'G', 'G#', 'A', 'A#', 'B']

### convert freq to pitch method (inc octaves)
def freq2pitch(freq):
pitch = 12 * math.log(freq/261.626) / math.log(2) #calculate relative to middle C4
note = noteName[int(round(pitch)) % 12] #get name
octave = (int(round(pitch)) / 12)+4 #get octave, offset from C(4)
return str(note + str(octave)) # no. semitones relative to C4

for i in range(1,length+1): #give &gt;length&lt; partials above root
freqSpectra.append(root*i)
noteSpectra.append(freq2pitch(root*i))

# print out data to .txt
print('Spectra as frequency (Hz) / closest note:')
file.write('Partial t Freq t Note n')
for i in range(length):
txt = str(i+1)+"t"+str(freqSpectra[i])+"t"+str(noteSpectra[i])+"n"
print i+1, "t",freqSpectra[i], "t", noteSpectra[i]
file.write(txt)

file.close()```

GitHubbed here.

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