I am learning prolog and have the following problem:
Reads an input file, line by line. Then write the sum of each line to the output file.
Given an input.txt input file of the following form:
1 2 7 4 5
3 1 0 7 9
Each entry line are integers separated by a space.
? - calculate (‘input.txt’, ’output.txt’).
Here is the content of the output.txt file:
19
20
I have tried many ways but still not working, hope someone can help me
go :-
setup_call_cleanup(
open('output.txt', write, Out),
forall(file_line_sum('input.txt', Sum), writeln(Out, Sum)),
close(Out)
).
file_line_sum(File, Sum) :-
file_line(File, Line),
line_sum(Line, Sum).
line_sum(Line, Sum) :-
split_string(Line, " ", "", NumsStr),
maplist(string_number, NumsStr, Nums),
sum_list(Nums, Sum).
string_number(Str, Num) :-
number_string(Num, Str).
file_line(File, Line) :-
setup_call_cleanup(
open(File, read, In),
stream_line(In, Line),
close(In)
).
stream_line(In, Line) :-
repeat,
read_line_to_string(In, Line1),
(Line1 == end_of_file -> !, fail ; Line = Line1).
Contents of input.txt:
1 2 7 4 5
3 1 0 7 9
123 456 7890
Result in swi-prolog:
?- time(go).
% 115 inferences, 0.001 CPU in 0.001 seconds (90% CPU, 195568 Lips)
Generated output.txt:
19
20
8469
Related
On follow samples, every line can be empty or can have some characters. The characters can be other than numbers too. Every line can have line feeds and tabs too.
Follow looks partly fine, a don't work with more complex content:
file1.txt
1
2
3
5
file2.txt
1
4
5
working with simple sample above:
comm -1 -3 file1.txt file2.txt
Output, which is fine
4
More complex sample, which don't fit
file1.txt
0
2
3
4
5
6
7
8
10
file2.txt
1
4
6
7
8
9
10
wrong output (the 10 should not on output on this sample)
1
9
10
If your sort the contend your file1.txt and file2.txt on the same way, before running your sample code, your sample code works fine.
You can do it on follow way:
sort file1.txt > file1_sorted.txt
sort file2.txt > file2_sorted.txt
After than, use the files above, for your code:
comm -1 -3 file1_sorted.txt file2_sorted.txt
I've been trying to search the Internet for answers but couldn't find any.
I'm trying to scan the following input:
100 0 1 3 10 3 6
101 0 4 4 2
200 1 2 5 1 2 3
300 1 7 6 1
Each line as a string and each string has whitespace between numbers.
I tried using:
while(scanf("%[^\n]s", str) != EOF)
but it's stuck in an infinite loop. It only scans the first line.
I also tried fgets until EOF but that gives me a compile error saying that I cannot compare a pointer
to an integer.
I just want to scan each line -> run it to a parser so I can separate the numbers into different variables -> do my calculations.
Thanks in advance.
I am just starting to learn ruby and I am having troubles splitting my strings by spaces.
First I read in my file and break them up by the newline character :
inputfile = File.open("myfile.in")
filelines = inputfile.read.split("\n")
Then I try to read each of the two numbers individually:
filelines.each_with_index {|val, index| do_something(val, index)}
Where do_something is defined as:
def do_something(value, index)
if index == 0
numcases = value
puts numcases
else
value.split(" ")
puts value
puts value[0] #trying to access the first number
puts value[1] #trying to access the second number
end
end
but with a smaller input file like this one,
42
4 2
11 19
0 10
10 0
-10 0
0 -10
-76 -100
5 863
987 850
My outputs ends up looking like this:
42
4 2
4
11 19
1
1
0 10
0
10 0
1
0
-10 0
-
1
0 -10
0
-76 -100
-
7
5 863
5
987 850
9
8
so what I am understanding is that it is breaking it up character by character, rather than by spaces. I know it can read in the whole line, as I can print the contents of the array in its entirety, but I dont know what I am doing wrong.
I have also tried replacing value.split(" ") with:
value.gsub(/\s+/m, ' ').strip.split(" ")
value.split
value.split("\s")
Using RubyMine 2017.3.2
As was said in the comments, plus some other points, with an idiomatic code sample:
lines = File.readlines('myfile.in')
header_line, data_lines = lines[0], lines[1..-1]
num_cases = header_line.to_i
arrays_of_number_strings = data_lines.map(&:split)
arrays_of_numbers = arrays_of_number_strings.map do |array_of_number_strings|
array_of_number_strings.map(&:to_i)
end
puts "#{num_cases} cases in file."
arrays_of_numbers.each { |a| p a }
File.readlines is super handy!
I don't think you were calling to_i on the header information, that
will be important.
The data_lines.map(&:split) will return an array of the numbers as strings, but then you'll need to convert those strings to numbers too.
The p a in the final line will use the Array#inspect method, which is handy for viewing arrays as arrays, e.g. [12, 34].
I have a file:
1 0.5
2 0.7
3 0.55
4 0.7
5 0.45
6 0.8
7 0.75
8 0.3
9 0.35
10 0.5
11 0.65
12 0.75
I want to split the file into 4 arrays ending on every next 3rd line and then to find the maximum value in the second column for every array. So this file the outcome would be the:
3 0.7
6 0.8
9 0.75
12 0.75
I have managed so far to split the file into several by
awk 'NR%3==1{x="L"++i;}{print > x}' filename
then to find the maximum in every file:
awk 'BEGIN{max=0}{if(($2)>max) max=($2)}END {print $1,max}'
However, this creates additional files which is fine for this example but in reality the original file contains 65 million lines so I will be a bit overwhelmed by the amount of files and I am trying to avoid it by writing a short script which will combine both of the mentioned above.
I tried this one:
awk 'BEGIN {for (i=1; i<=12; i+=3) {max=0} {if(($2)>max) max=($2)}}END {print $1,max}' Filename
but it produces something irrelevant.
So if you can help me out it will be much appreciated!
You could go for something like this:
awk 'NR % 3 == 1 || $2 > max {max = $2} NR % 3 == 0 {print $1, max}' file
The value of max is always reset every three rows and updated if value of the second column is greater than it. At the end of every group of three, the first column and the max are printed.
I'm quite new to awk, that I am using more and more to process the output files from a model I am running. Right now, I am stuck with a multiplication issue.
I would like to calculate relative change in percentage.
Example:
A B
1 150 0
2 210 10
3 380 1000
...
I would like to calculate Ax = (Ax-A1)/A1 * 100.
Output:
New_A B
1 0 0
2 10 40
3 1000 153.33
...
I can multiply columns together but don't know how to fix a value to a position in the text file (ie. Row 1 Column 1).
Thank you.
Assuming your actual file does not have the "A B" header and the row numbers in it:
$ cat file
150 0
210 10
380 1000
$ awk 'NR==1 {a1=$1} {printf "%s %.1f\n", $2, ($1-a1)/a1*100}' file | column -t
0 0.0
10 40.0
1000 153.3