Faster algorithm/language for string replacement [closed] - awk

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EDIT:
Method 3 provided below is way faster by testing, reduce the estimated runtime from 2-3 days to < 1 day.
I had a sample file with a long string >50M like this.
CACTGCTGTCACCCTCCATGCACCTGCCCACCCTCCAAGGATCNNNNNNNCACTGCTGTCACCCTCCATGCACCTGCCCACCCTCCAAGGATCaagctCCgaTNNNNNNNNNNNNGgtgtgtatatatcatgtgtgGCCCTAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGatgtgtggtgtgtggggttagggttagggttaNNNNNNNNNNNCCCTCCAAGGATCaagctCCgaTNNNNNNNNNNNNGgtgtgtatataGCCCTAGGtcatgtgtgatgtgtggtgtgtggggttagggttagggttaNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGCCCTAGGNNNNNNNGCCCTAGGNNNNNNNNNNNNNNAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgttggggtNNNNNNGgtgtgtatatatcatagggAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgtggtgtgggtgtgtggggttagggAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtggtgtgtggggttagggttagggttaNNNNNNNNNNNNtgttgttttattttcttacaggtggtgtgtggggttagggttagggttaNNNNNNNNNNNCCCTCCAAGGATCaagctCCgaTNNNNNNNNNNNNGgtgtgtatatatcatgtAGCCCTAGGGatgtgtggtgtgtggggttagggttagggttaNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNttgtggtgtgtggtgNNNNNAGGGCtggtgtgtggggttagggAtagggAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgtggtgtgtggggGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgtggtgtgtggggttagggNNNNNNNNNNNNNNNNNNNNNNNNNNNNAGaggcatattgatcCCCTCCAAGGATCaagctCCgaTNNNNNNNggttagggttNNNNNGgtgtCCCTAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgtggtgtgtggggttagggttagggttaNNNNNNNNNNNNtgttgttttattttcttacaggtggtgtgtggggttagggttagggttaNNNNNNNNNNNCCCTCCAAGGATCaagctCCgaTNNNNNNNNNNNNGgtgtgtatatatcatgtAGCCCTAGGGatgtgtggtgtgtggggttagggttagggttaNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNttgtggtgtgtggtgNNNNNAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgttggggtNNNNNNGgtgtgtatatatcatagggAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgatgtgtggtgtgggtgtgtggggttagggAGGGCCCTAGGGCCCTAtgtgtgGCCCTAGGGCtgtgtgGCCCTAGGGCGGagtatatatcatgtgtgNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
For everything substring with length k = 50 (which means there are
length(file)-k+1 substring)
if the A||T||a||t (Upper & Lower case) is >40%,
replace every character in that substring with N or n (preserving
case).
Sample output:
CACTGCTGTCACCCTCCATGCACCTGCCCACCCTCCAAGGATCNNNNNNNCACTGCTGTCACCCTCCATGCACCTGCCCACCCTCCAAGGATCaagctCCgaTNNNNNNNNNNNNGgnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnggttaNNNNNNNNNNNNNNNNNNNNNNNNnnnnnNNnnNNNNNNNNNNNNNNnnnnnnnnnnnNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGCCCTAGGNNNNNNNGCCCTAGGNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNNNnnnnnNNnnNNNNNNNNNNNNNNnnnnnnnnnnnnnnnnnNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNttgtggtgtgtggtgNNNNNAGGNNnnnnnnnnnnnnnnnnnnNnnnnnNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggttagggNNNNNNNNNNNNNNNNNNNNNNNNNNNNAGaggcatattgatcCCCTCCAAGGATCaagctCCgaTNNNNNNNggttagggttNNNNNGnnnnNNNNNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNNNnnnnnNNnnNNNNNNNNNNNNNNnnnnnnnnnnnnnnnnnNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNttgtggtgtgtggtgNNNNNNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnNNNNNNNNNNNNNNNNNnnnnnnNNNNNNNNNNnnnnnnNNNNNNNNNNNNnnnnnnnnnnnnnnnngNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
I was using AWK in command line for ease, but it just runs extremely slow with string replacement... and consume only <5% CPU somehow
Code: https://repl.it/#hey0wing/DutifulHandsomeMisrac-2
# Method 1
cat chr22.fa | head -n1 > chr22.masked.fa
cat chr22.fa | tail -n+2 | awk -v k=100 -v r=40 '{
printf("chr22.fa: %d\n",length($0))
i = 1;
while (i <= length($0)-k+1) {
x = substr($0, i, k)
if (i == 1) {
rate = gsub(/A/,"A",x) + gsub(/T/,"T",x) + gsub(/a/,"a",x) + gsub(/t/,"t",x)
} else {
prevx = substr($0,i-1,1)
if (prevx == "A" || prevx == "a" || prevx == "T" || prevx == "t")
rate -= 1
nextx = substr(x,k,1)
if (nextx == "A" || nextx == "a" || nextx == "T" || nextx == "t")
rate += 1
}
if (rate>r*k/100) {
h++
highGC[i] = i
}
printf("index-r:%f%% high-AT:%d \r",i/(length($0)-k+1)*100,h)
i += 1
}
printf("index-r:%f%% high-AT:%d\n\n",i/(length($0)-k+1)*100,h)
for (j in highGC) {
y = highGC[j]
SUB++
printf("sub-r:%f%% \r",SUB/h*100)
x = substr($0, y, k)
gsub (/[AGCT]/,"N",x)
gsub (/[agct]/,"n",x)
$0 = substr($0,1,y-1) x substr($0,y+k)
}
printf("sub-r:%f%%\nsubstituted:%d\n\n",SUB/h*100,SUB)
printf("%s",$0) >> "chr22.masked.fa"
}'
# Method 2
cat chr22.fa | head -n1 > chr22.masked2.fa
cat chr22.fa | tail -n+2 | awk -v k="100" -v r=40 '{
printf("chr22.fa: %d\n",length($0))
i = 1;
h = 0;
while (i<=length($0)-k+1) {
x = substr($0, i, k)
rate = gsub(/[ATX]/,"X",x) + gsub(/[atx]/,"x",x)
if (rate>r/k*100) {
h++
gsub (/[GC]/,"N",x)
gsub (/[gc]/,"n",x)
$0 = substr($0,1,i-1) x substr($0,i+k)
}
printf("index-r:%f%% sub-r:%f%% \r",i/(length($0)-k+1)*100,h/544*100)
i += 1
}
gsub (/X/,"N",$0)
gsub (/x/,"n",$0)
printf("index-r:%f%% sub-r:%f%% \n",i/(length($0)-k+1)*100,h/544*100)
printf("%s",$0) >> "chr22.masked2.fa"
}'
# Method 3
cat chr22.fa | head -n1 > chr22.masked3.fa
cat chr22.fa | tail -n+2 | awk -v k="100" -v r=40 '{
printf("chr22.fa: %d\n",length($0))
i = 1;
h = 0;
while (i <= length($0)-k+1) {
x = substr($0, i, k)
rate = gsub(/A/,"A",x) + gsub(/T/,"T",x) + gsub(/a/,"a",x) + gsub(/t/,"t",x)
if (rate>r/k*100) {
h++
gsub(/[ACGT]/,"N",x)
gsub(/[acgt]/,"n",x)
if (i == 1) {
s = x
} else {
s = substr(s,1,length(s)-k+1) x
}
} else {
if (i == 1) {
s = x
} else {
s = s substr(x,k,1)
}
}
printf("index-r:%f%% sub-r:%f%% \r",i/(length($0)-k+1)*100,h/544*100)
i += 1
}
printf("index-r:%f%% sub-r:%f%% \n\n",i/(length($0)-k+1)*100,h/544*100)
printf("%s",s) >> "chr22.masked3.fa"
}'
The estimated runtime is around 2-3 days ...
Are there any faster algorithm for this problem? If no, are there any language can perform string replacement faster?
More info:
the AWK command consume ~30% CPU at WSL & GitBash, but only ~5% on windows cmd with an OpenSSH client, where the progress rate is similar

Answer 1

Okay, there's an O(n) solution that involves a sliding window on to your data set. The following algorithm should suffice:
set window to ""
while true:
if window is "":
read k characters into window, exit while if less available
set atCount to number of characters in window matching "AaTt".
if atCount > 40% of k:
for each char in window:
if char uppercase:
output "N"
else:
output "n"
window = ""
else:
if first character of window matches "AaTt":
decrease atCount
remove first character of window
read next character into end of window, exit while if none available
if last character of window matches "AaTt":
increase atCount
What this does is to run a sliding window through your data, at each point testing if the proportion of AaTt characters in that window is more than 40%.
If so, it outputs the desired Nn characters and reloads the next k-sized window.
If it's not over 40%, it removes the first character in the windows and adds the next one to the end, adjusting the count of AaTt characters correctly.
If, at any point, there aren't enough characters left to satisfy a check (k when loading a full window, or 1 when sliding), it exits the loop.

Answer 2

Try some perl:
perl -slpe '
my $len = length;
for (my $i = 0; $i < $len; $i += $k) {
my $substring = substr($_, $i, $k);
my $count = $substring =~ tr/aAtT/aAtT/;
if ($count >= $k * $threshold) {
$substring =~ s/[[:lower:]]/n/g;
$substring =~ s/[[:upper:]]/N/g;
substr($_, $i, $k) = $substring;
}
}
' -- -k=50 -threshold=0.4 file