I am trying to write a bash script that will be able to do inverse modulo operations.
Currently the program can do regular mod calculations but trying to do inverse modulo operations leaves me with wrong answers (either prints 0's or wrong answers).
Is it even possible to do inverse calculations, if so what would be the formula?
Expected Result:
28 14 22 30 18 32 30 12 25 37 8 31 18 4 37 3 33 35 27 2 4 3 28
Gotten Results:
-23 -4 -29 -27 -17 -10 -27 -25 -24 -11 -37 -5 -17 -32 -11 -15 -6 -35 -39 -22
#!/bin/bash
flag_enc=(268 413 110 190 426 419 108 229 310 379 323 373 385 236 92 96 169 321 284 185 154 137 186) #inputs
for i in "${flag_enc[#]}"
do
mod=$((1 / $i)) # input^(-1)
modus=$(($mod % 41)) #mod41 calculation
echo "$modus"
done
Oguz Ismail gave the right mathematical expression for calculating inverse mod in bash. I am attaching the modified the script bellow:
flag_enc=(268 413 110 190 426 419 108 229 310 379 323 373 385 236 92 96 169 321 284 185 154 137 186)
m=41
for i in "${flag_enc[#]}"
do
for ((x = 1; x < m; x++)); do
if ((($i % m) * (x % m) % m == 1)); then
echo $x
fi
done
done
I don't know if your algorithm is correct or not, but bash doesn't support floating point arithmetic intrinsically.
So either use bc, or define a function like below
mmi() {
a=$1
m=$2
for ((x = 1; x < m; x++)); do
if (((a % m) * (x % m) % m == 1)); then
echo $x
return 0
fi
done
return 1
}
and use it like so:
$ mmi 268 41
28
Better use a dedicated tool or programming language. Example with the gmpy2 module of python (without error handling, this is left as an exercise):
for i in "${flag_enc[#]}"; do
mod=$(printf 'import gmpy2\nprint(int(gmpy2.invert(%d, %d)))\n' "$i" "41" | python)
echo "$mod"
done
Related
I want to generate a sequence of integer numbers between 2 included bounds. I tried with seq, but I could only get the following:
$ low=10
$ high=100
$ n=8
$ seq $low $(( (high-low) / (n-1) )) $high
10
22
34
46
58
70
82
94
As you can see, the 100 is not included in the sequence.
I know that I can get something like that using jot:
$ jot 8 10 100
10
23
36
49
61
74
87
100
But the server I use does not have jot installed, and I do not have permission to install it.
Is there a simple method that I could use to reproduce this behaviour without jot?
If you don't mind launching an extra process (bc) and if it's available on that machine, you could also do it like this:
$ seq -f'%.f' 10 $(bc <<<'scale=2; (100 - 10) / 7') 100
10
23
36
49
61
74
87
100
Or, building on oguz ismail's idea (but using a precision of 4 decimal places):
$ declare -i low=10
$ declare -i high=100
$ declare -i n=8
$ declare incr=$(( (${high}0000 - ${low}0000) / (n - 1) ))
$
$ incr=${incr::-4}.${incr: -4}
$
$ seq -f'%.f' "$low" "$incr" "$high"
10
23
36
49
61
74
87
100
You can try this naive implementation of jot:
jot_naive() {
local -i reps=$1 begin=${2}00 ender=${3}00
local -i x step='(ender - begin) / (reps - 1)'
for ((x = begin; x <= ender; x += step)); do
printf '%.f\n' ${x::-2}.${x: -2}
done
}
You could use awk for that:
awk -v reps=8 -v begin=10 -v end=100 '
BEGIN{
step = (end - begin) / (reps-1);
for ( f = i = begin; i <= end; i = int(f += step) )
print i
}
'
10
22
35
48
61
74
87
100
UPDATE 1 ::: fixed double-printing of final row due to difference less than tiny value of epsilon
to maintain directional consistency, rounding is performed based on sign of final :
—- e.g. if final is negative, then any rounding is done as if the current step value (CurrSV) is negative, regardless of sign of CurrSV
———————————————
while i haven't tested every single possible edge case, i believe this version of the code should handle both positive and negative rounding properly, for the most part.
that said, this isn't a jot replacement at all - it only implements a very small subset of the steps counting feature instead of being a full blown clone of it:
{m,g}awk '
function __________(_) {
return -_<+_?_:-_
}
BEGIN {
CONVFMT = "%.250g"; OFMT = "%.13f"
_____ = (_+=_^=_______=______="")^-_^!_
} {
____ = (((_=$(__=(___=$NF)^(_<_)))^(_______=______="")*___\
)-(__=$++__))/--_
_________ = (_____=(-(_^=_<_))^(________=+____<-____\
)*(_/++_))^(++_^_++-+_*_--+-_)
if (-___<=+___) {
_____=__________(_____)
_________=__________(_________)
}
do { print ______,
++_______, int(__+_____), -____+(__+=____)
} while(________? ___<(__-_________) : (__+_________)<___)
print ______, ++_______, int(___+_____), ___, ORS
}' <<< $'8 -3 -100\n8 10 100\n5 -15 -100\n5 15 100\n11 100 11\n10 100 11'
|
1 -3 -3
2 -17 -16.8571428571429
3 -31 -30.7142857142857
4 -45 -44.5714285714286
5 -58 -58.4285714285714
6 -72 -72.2857142857143
7 -86 -86.1428571428572
8 -100 -100
1 10 10
2 23 22.8571428571429
3 36 35.7142857142857
4 49 48.5714285714286
5 61 61.4285714285714
6 74 74.2857142857143
7 87 87.1428571428572
8 100 100
1 -15 -15
2 -36 -36.2500000000000
3 -58 -57.5000000000000
4 -79 -78.7500000000000
5 -100 -100
1 15 15
2 36 36.2500000000000
3 58 57.5000000000000
4 79 78.7500000000000
5 100 100
1 100 100
2 91 91.1000000000000
3 82 82.2000000000000
4 73 73.3000000000000
5 64 64.4000000000000
6 55 55.5000000000000
7 47 46.6000000000000
8 38 37.7000000000000
9 29 28.8000000000000
10 20 19.9000000000000
11 11 11
1 100 100
2 90 90.1111111111111
3 80 80.2222222222222
4 70 70.3333333333333
5 60 60.4444444444445
6 51 50.5555555555556
7 41 40.6666666666667
8 31 30.7777777777778
9 21 20.8888888888889
10 11 11
I have a tab file with two columns like that
5 6 14 22 23 25 27 84 85 88 89 94 95 98 100 6 94
6 8 17 20 193 205 209 284 294 295 299 304 305 307 406 205 284 307 406
2 10 13 40 47 58 2 13 40 87
and the desired output should be
5 6 14 22 23 25 27 84 85 88 89 94 95 98 100 14 27
6 8 17 20 193 205 209 284 294 295 299 304 305 307 406 6 209 299 305
2 10 13 23 40 47 58 87 10 23 40 58
I would like to change the numbers in 2nd column for random numbers in 1st column resulting in an output in 2nd column with the same number of numbers. I mean e.g. if there are four numbers in 2nd column for x row, the output must have four random numbers from 1st column for this row, and so on...
I'm try to create two arrays by AWK and split and replace every number in 2nd column for numbers in 1st column but not in a randomly way. I have seen the rand() function but I don't know exactly how joint these two things in a script. Is it possible to do in BASH environment or are there other better ways to do it in BASH environment? Thanks in advance
awk to the rescue!
$ awk -F'\t' 'function shuf(a,n)
{for(i=1;i<n;i++)
{j=i+int(rand()*(n+1-i));
t=a[i]; a[i]=a[j]; a[j]=t}}
function join(a,n,x,s)
{for(i=1;i<=n;i++) {x=x s a[i]; s=" "}
return x}
BEGIN{srand()}
{an=split($1,a," ");
shuf(a,an);
bn=split($2,b," ");
delete m; delete c; j=0;
for(i=1;i<=bn;i++) m[b[i]];
# pull elements from a upto required sample size,
# not intersecting with the previous sample set
for(i=1;i<=an && j<bn;i++) if(!(a[i] in m)) c[++j]=a[i];
cn=asort(c);
print $1 FS join(c,cn)}' file
5 6 14 22 23 25 27 84 85 88 89 94 95 98 100 85 94
6 8 17 20 193 205 209 284 294 295 299 304 305 307 406 20 205 294 295
2 10 13 23 40 47 58 87 10 13 47 87
shuffle (standard algorithm) the input array, sample required number of elements, additional requirement is no intersection with the existing sample set. Helper structure map to keep existing sample set and used for in tests. The rest should be easy to read.
Assuming that there is a tab delimiting the two columns, and each column is a space delimited list:
awk 'BEGIN{srand()}
{n=split($1,a," ");
m=split($2,b," ");
printf "%s\t",$1;
for (i=1;i<=m;i++)
printf "%d%c", a[int(rand() * n) +1], (i == m) ? "\n" : " "
}' FS=\\t input
Try this:
# This can be an external file of course
# Note COL1 and COL2 seprated by hard TAB
cat <<EOF > d1.txt
5 6 14 22 23 25 27 84 85 88 89 94 95 98 100 6 94
6 8 17 20 193 205 209 284 294 295 299 304 305 307 406 205 284 307 406
2 10 13 40 47 58 2 13 40 87
EOF
# Loop to read each line, not econvert TAB to:, though could have used IFS
cat d1.txt | sed 's/ /:/' | while read LINE
do
# Get the 1st column data
COL1=$( echo ${LINE} | cut -d':' -f1 )
# Get col1 number of items
NUM_COL1=$( echo ${COL1} | wc -w )
# Get col2 number of items
NUM_COL2=$( echo ${LINE} | cut -d':' -f2 | wc -w )
# Now split col1 items into an array
read -r -a COL1_NUMS <<< "${COL1}"
COL2=" "
# THis loop runs once for each COL2 item
COUNT=0
while [ ${COUNT} -lt ${NUM_COL2} ]
do
# Generate a random number to use as teh random index for COL1
COL1_IDX=${RANDOM}
let "COL1_IDX %= ${NUM_COL1}"
NEW_NUM=${COL1_NUMS[${COL1_IDX}]}
# Check for duplicate
DUP_FOUND=$( echo "${COL2}" | grep ${NEW_NUM} )
if [ -z "${DUP_FOUND}" ]
then
# Not a duplicate, increment loop conter and do next one
let "COUNT = COUNT + 1 "
# Add the random COL1 item to COL2
COL2="${COL2} ${COL1_NUMS[${COL1_IDX}]}"
fi
done
# Sort COL2
COL2=$( echo ${COL2} | tr ' ' '\012' | sort -n | tr '\012' ' ' )
# Print
echo ${COL1} :: ${COL2}
done
Output:
5 6 14 22 23 25 27 84 85 88 89 94 95 98 100 :: 88 95
6 8 17 20 193 205 209 284 294 295 299 304 305 307 406 :: 20 299 304 305
2 10 13 40 47 58 :: 2 10 40 58
I want to use a shell scrip in a for-loop that run 100 files in parallel.
Currently, I have a shell script of the following format:
#!/bin/bash
NUM=10
python a1.py $((NUM + 0)) &
python a2.py $((NUM + 2)) &
python a3.py $((NUM + 4)) &
python a4.py $((NUM + 6)) &
python a5.py $((NUM + 8)) &
Now, if I have a1.py, a2.py, a3.py .... a100.py, and I want to run them in parallel, how do I do it in for-loop?
If you have bash version 4 and run this:
echo {10..208..2}
You will get this:
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60
62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108
110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140 142 144 146
148 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178 180 182 184
186 188 190 192 194 196 198 200 202 204 206 208
which looks like your series. Then, if you want to run lots of jobs in parallel, I would use GNU Parallel. That offers you {#} as a placeholder for the job number. So, if you run this:
parallel -k echo {#} {} ::: {10..208..2}
You will get this:
1 10
2 12
3 14
4 16
5 18
So, to run your actual scripts, something like:
parallel -k --dry-run 'python a{#}.py {}' ::: {10..208..2}
Sample Output
python a1.py 10
python a2.py 12
python a3.py 14
python a4.py 16
...
...
If that looks good, run again without the --dry-run and without the -k which keeps the output in order to make it easier to debug.
TLDR;
My most concise answer, with GNU Parallel is:
parallel python a{#}.py {} ::: {10..208..2}
Or if you don't have bash version 4:
parallel python a{#}.py {} ::: $(seq 10 2 208)
NUM=10
for ((i=0; i<100; i++)); do echo python a$(($i+1)).py $(($NUM+$i*2)); done
Output:
python a1.py 10
python a2.py 12
python a3.py 14
.
.
.
python a98.py 204
python a99.py 206
python a100.py 208
If this looks okay, use:
NUM=10
for ((i=0; i<100; i++)); do python a$(($i+1)).py $(($NUM+$i*2)) & done
I wrote this in response to Reddit's daily programmer challenge, and I would like to get some of your feedback on it to improve the code (it seems to work). The challenge is as follows:
We are given a list of numbers in a "short-hand" range notation where only the significant part of the next number is written because we know the numbers are always increasing (ex. "1,3,7,2,4,1" represents [1, 3, 7, 12, 14, 21]). Some people use different separators for their ranges (ex. "1-3,1-2", "1:3,1:2", "1..3,1..2" represent the same numbers [1, 2, 3, 11, 12]) and they sometimes specify a third digit for the range step (ex. "1:5:2" represents [1, 3, 5]).
NOTE: For this challenge range limits are always inclusive.
Our job is to return a list of the complete numbers.
The possible separators are: ["-", ":", ".."]
Sample input:
104..02
545,64:11
Sample output:
104 105 106...200 201 202 # truncated for simplicity
545 564 565 566...609 610 611 # truncated for simplicity
My solution:
BEGIN { FS = "," }
function next_value(current_value, previous_value) {
regexp = current_value "$"
while(current_value <= previous_value || !(current_value ~ regexp)) {
current_value += 10
}
return current_value;
}
{
j = 0
delete number_list
for(i = 1; i <= NF; i++) {
# handle fields with ranges
if($i ~ /-|:|\.\./) {
split($i, range, /-|:|\.\./)
if(range[1] > range[2]) {
if(j != 0) {
range[1] = next_value(range[1], number_list[j-1])
range[2] = next_value(range[2], range[1])
}
else
range[2] = next_value(range[2], range[1]);
}
if(range[3] == "")
number_to_iterate_by = 1;
else
number_to_iterate_by = range[3];
range_iterator = range[1]
while(range_iterator <= range[2]) {
number_list[j] = range_iterator
range_iterator += number_to_iterate_by
j++
}
}
else {
number_list[j] = $i
j++
}
}
# apply increasing range logic and print
for(i = 0; i < j; i++ ) {
if(i == 0) {
if(NR != 1) printf "\n"
current_value = number_list[i]
}
else {
previous_value = current_value
current_value = next_value(number_list[i], previous_value)
}
printf "%s ", current_value
}
}
END { printf "\n" }
This is BASH (Not AWK).
I believe it is a valid answer because the original challenge doesn't specify a language.
#!/bin/bash
mkord(){ local v=$1 dig base
max=$2
(( dig=10**${#v} , base=max/dig*dig , v+=base ))
while (( v < max )); do (( v+=dig )); done
max=$v
}
while read line; do
line="${line//[,\"]/ }" line="${line//[:-]/..}"
IFS=' ' read -a arr <<<"$line"
max=0 a='' res=''
for val in "${arr[#]//../ }"; do
IFS=" " read v1 v2 v3 <<<"$val"
(( a==0 )) && max=$v1
[[ $v1 ]] && mkord "$v1" "$max" && v1=$max
[[ $v2 ]] && mkord "$v2" "$max" && v2=$max
res=$res${a:+,}${v2:+\{}$v1${v2:+\.\.}$v2${v3:+\.\.}$v3${v2:+\}}
a=1
done
(( ${#arr[#]} > 1 )) && res={$res}
eval set -- $res
echo "\"$*\""
done <"infile"
If the source of the tests is:
$ cat infile
"1,3,7,2,4,1"
"1-3,1-2"
"1:5:2"
"104-2"
"104..02"
"545,64:11"
The result will be:
"1 3 7 12 14 21"
"1 2 3 11 12"
"1 3 5"
"104 105 106 107 108 109 110 111 112"
"104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202"
"545 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611"
This gets the list done in 7 milliseconds.
My solution using gawk, RT (It contains the input text that matched the text denoted by RS) and next_n function uses modulo operation for to find the next number based on the last
cat range.awk
BEGIN{
RS="\\.\\.|,|:|-"
start = ""
end = 0
temp = ""
}
function next_n(n, last){
mod = last % (10**length(n))
if(mod < n) return last - mod + n
return last + ((10**length(n))-mod) + n
}
{
if(RT==":" || RT==".." || RT=="-"){
if(start=="") start = next_n($1,end)
else temp = $1
}else{
if(start != ""){
if(temp==""){
end = next_n($1,start)
step = 1
}else {
end = next_n(temp,start)
step = $1
}
for(i=start; i<=end; i+=step) printf "%s ", i
start = ""
temp = ""
}else{
end = next_n($1,end)
printf "%s ", end
}
}
}
END{
print ""
}
TEST 1
echo "104..02" | awk -f range.awk
OUTPUT 1
104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202
TEST 2
echo "545,64:11" | awk -f range.awk
OUTPUT 2
545 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611
TEST 3
echo "2..5,7,2-1,2:1,0-3,2-7,8..0,4,4,2..1" | awk -f range.awk
OUTPUT 3
2 3 4 5 7 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 40 41 42 43 52 53 54 55 56 57 58 59 60 64 74 82 83 84 85 86 87 88 89 90 91
TEST 4 with step
echo "1:5:2,99,88..7..3" | awk -f range.awk"
OUTPUT 4
1 3 5 99 188 191 194 197
I'm having a little bit of trouble with a bash script that is intended to produce a random number between 100 and 999.
My script is as follows:
for i in {1..1000}
do
pin=$((( $RANDOM % 999) +100))
echo $pin
done
Below is a sample of the output. As you can see, some of the numbers exceed 999. What might be going on here?
626
901
1094
456
290
1047
265
221
483
626
848
198
879
474
993
205
200
229
391
325
306
201
800
1004
694
While ($RANDOM % 999) is in range 0 to 999, your output is (($RANDOM % 999) + 100), which is in range 100 to 1099. Is (($RANDOM + 100) % 999) instead of (($RANDOM % 999) + 100) what you want?
To emit 1000 numbers between 100 and 999:
for ((i=0; i<1000; i++)); do
echo "$(( ( RANDOM % 900 ) + 100 ))"
done
Keep in mind that 900 % 900 is 0, meaning that the maximum value possible as output is 899, so if you want your values (after addition) to be through 999 inclusive, you use 900, not 899.