Question

Many thanks to the SO community for helping me with the previous problems I had encountered. Love the help here!

I have yet another problem now. I have a flat list of DNA sequences that have associated “Construct Number” and “Part Number. As things stand right now, from my previous code, I have it as a csv file which I open up, read in, and import as a list of dictionary objects. Everything is sorted by “Construct Number” already, but I need to then sort by “Part Number”. (It’s sort of like in Excel, where they say “First sort by and then sort by _.”

Does anybody know how to get this done? Thus far, all I have written is this:

primers_list = open('primers-list.csv', 'rU')
primers_unsorted = csv.DictReader(primers_list)
for row in primers_unsorted:
    print(row)

A subset of the output thus far is just the following, for visualization of the data I’m working with:

{' Direction': 'fw primer', ' Construct Number': '1', ' Part Number': '2', 'Primer Sequence': 'AAGCGGCCGCTCGAGTCTAAgctcactcaaaggcggtaatcagataaaaaaaatccttag'}
{' Direction': 're primer', ' Construct Number': '1', ' Part Number': '1', 'Primer Sequence': 'attaccgcctttgagtgagcTTAGACTCGAGCGGCCGCTTTTTGACACCAGACCAACTGG'}
{' Direction': 'fw primer', ' Construct Number': '1', ' Part Number': '1', 'Primer Sequence': 'TTTAATTACTAACTTTATCTATGATAGATCCCGTCGTTTTACAACGTCGTGACTGGGAAA'}
{' Direction': 're primer', ' Construct Number': '1', ' Part Number': '2', 'Primer Sequence': 'AAAACGACGGGATCTATCATAGATAAAGTTAGTAATTAAACTTAAAAGTTGTTTAATGTC'}
{' Direction': 'fw primer', ' Construct Number': '2', ' Part Number': '2', 'Primer Sequence': 'gtaaatccaagttgtaataatactagagTAGCATAACCCCTTGGGGCCTCTAAACGGGTC'}
{' Direction': 're primer', ' Construct Number': '2', ' Part Number': '1', 'Primer Sequence': 'GGGGTTATGCTActctagtattattacaacttggatttaccacctttcttcgccttgatc'}
{' Direction': 'fw primer', ' Construct Number': '2', ' Part Number': '1', 'Primer Sequence': 'TACGACTCACTATAGGGAGAtactagagttaaggaggtaaaaaaaatgggtccggtcgtt'}
{' Direction': 're primer', ' Construct Number': '2', ' Part Number': '2', 'Primer Sequence': 'ttacctccttaactctagtaTCTCCCTATAGTGAGTCGTATTACTCTAGAAGCGGCCGCg'}
{' Direction': 'fw primer', ' Construct Number': '3', ' Part Number': '2', 'Primer Sequence': 'gtaaatccaagttgtaataatactagagTAGCATAACCCCTTGGGGCCTCTAAACGGGTC'}
{' Direction': 're primer', ' Construct Number': '3', ' Part Number': '1', 'Primer Sequence': 'GGGGTTATGCTActctagtattattacaacttggatttaccacctttcttcgccttgatc'}
{' Direction': 'fw primer', ' Construct Number': '3', ' Part Number': '1', 'Primer Sequence': 'TAACTATCACTATAGGGAGAtactagagttaaggaggtaaaaaaaatgggtccggtcgtt'}
{' Direction': 're primer', ' Construct Number': '3', ' Part Number': '2', 'Primer Sequence': 'ttacctccttaactctagtaTCTCCCTATAGTGATAGTTATTACTCTAGAAGCGGCCGCg'}

Answer 1

Another way:

import operator
primers_unsorted.sort(key=operator.itemgetter(' Construct Number', ' Part Number'))

for row in primers_unsorted:
    print(row)