N50 and N90

The N50 contig size is a weighted median value and defined as

the length of the smallest contig S in the sorted list of all

contigs where the cumulative length from the largest contig to

contig S is at least 50% of the total length.

perl -e 'my ($len,$total)=(0,0);my @x;while(<>){if(/^($len>0){$total+=$len;push @x,$len;}@x=sort{$b<=>$a}@x; my ($count,$half)=(0,0);for (my $j=0;$j<@x;$j++){$count+=$x[$j;if(($count>=$total/2)&&($half==0)){print "N50: $x$j}elsif($count>=$total*0.9){print" target="_blank" rel="noopener">"N90: $x[$j\n";exit;}}'  contigs.fahttp://seqanswers.com/forums/showthread.php?t=2766

N50 N90 calculation using Perl code 

http://seqanswers.com/forums/showthread.php?t=2766