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#!/usr/bin/awk -f
### lpf.awk
# Low Pass Filter with Hardcoded FIR Window
BEGIN {
OFS = FS
sign = "[+-]?"
decimal = "[0-9]+[.]?[0-9]*"
fraction = "[.][0-9]*"
exponent = "([Ee]" sign "[0-9]+)?"
number = "^" sign "(" decimal "|" fraction ")" exponent "$"
#H = ARGV[1]
#H = 1.0
#H = "1.00 1.00 1.00" # rect
#H = "0.25 0.50 0.25" # von Hann
H = "0.23 0.54 0.23" # Hamming
window_size = split(H, H_arr, "[ ]*")
}
NR == 1 {
for (y=1; y<=NF; y++)
($y ~ number) ? header[y] = "col" y : header[y] = $y
}
NF > 0 {
if (NF > nf_max)
nf_max = NF
input_size = window_size
output_size = (input_size + window_size - 1)
### columns
for (y=1; y<=nf_max; y++) {
if ($y == header[y])
printf(header[y] OFS header[y] "_lpf")
if ($y ~ number) {
count[y]++
# rotate input buffer
for (n=1; n<=input_size; n++) {
X_arr[y,n] = X_arr[y,n+1]
}
X_arr[y,input_size] = $y
Y[y] = 0
for (n=1; n<=window_size; n++) {
for (m=1; m<=input_size; m++) {
if (n <= window_size) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
if ((n > window_size) && (n <= input_size)) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
if ((n > window_size) && (n > input_size)) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
else {
Y[y] += 0
continue
}
}
}
printf(X_arr[y,input_size] OFS Y[y])
}
if (y < nf_max)
printf(OFS)
else
printf(ORS)
}
}
END {
### rows
for (x=1; x<=window_size; x++) {
### columns
for (y=1; y<=nf_max; y++) {
# rotate input buffer
for (n=1; n<=input_size; n++) {
X_arr[y,n] = X_arr[y,n+1]
#print X_arr[y,n]
}
#delete X_arr[y,input_size]
#input_size = length(X_arr)
#print length(X_arr)
Y[y] = 0
for (n=1; n<=window_size; n++) {
for (m=1; m<=input_size; m++) {
if (n <= window_size) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
if ((n > window_size) && (n <= input_size)) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
if ((n > window_size) && (n > input_size)) {
Y[y] += H_arr[n-m+1]*X_arr[y,m]
continue
}
else {
Y[y] += 0
continue
}
}
}
printf(X_arr[y,input_size] OFS Y[y])
if (y < nf_max)
printf(OFS)
else
printf(ORS)
X_arr[input_size] = 0
}
}
}
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