SQL like group by and sum for text files in command line?

Question

I have huge text files with two fields, the first is a string the second is an integer. The files are sorted by the first field. What I'd like to get in the output is one line per unique string and the sum of the numbers for the identical strings. Some strings appear only once while other appear multiple times. E.g. Given the sample data below, for the string glehnia I'd like to get 10+22=32 in the result.

Any suggestions how to do this either with gnuwin32 command line tools or in linux shell?

Thanks!

glehnia 10
glehnia 22
glehniae 343
glehnii 923
glei 1171
glei 2283
glei 3466
gleib 914
gleiber 652
gleiberg 495
gleiberg 709

Answer 1

In AWK, you could do something like this:

awk '($1 == last) || (last == "") {sum += $2}
     ($1 != last) && (last != "") {print last " " sum; sum = $2}
                                  {last = $1}
     END                          {print last " " sum}' huge_text_file.txt

Answer 2

This type of queries are most easily and flexibly done in SQL. You can use SQLet and SQLite for that purpose:

sqlet.py -d' ' -A file1.txt 'select a1, sum(a2) from A group by a1' | sqlite3

Answer 3

You could a use a few lines of Lua to acheive this. Lua is available on a wide range of platforms including Windows and Linux.

-- Quick and dirty - no error checking, unsorted output

io.input('huge_text_file.txt')

results = {}

for line in io.lines() do
    for text, number in string.gmatch(line, '(%w+)%s+(%d+)') do
        results[text] = (results[text] or 0) + number
    end
end

for text, number in pairs(results) do
    print(text, number)
end

You can sort the output using any sort utility or a few more lines of Lua.