Dear All, Thanks to the help I got from the list, I was able to (almost) finish a script that performs some data postprocessing (and the code is really amazingly short). Now, there are a few things left. Consider the lists bs = [4,5,3,1,5,2,7,2,8,2,2,3,3,5,6,7] and ms = [2,2,2,2,4,4,4,4,6,6,4,4,4,10,12,14] Now, I would like to sort bs (and that is easy) and then (since there is a 1-1 correspondence between the elements in ms and bs) re-order the elements in ms accordingly i.e. bs would become [1,2,2,2,2,3,3,3,4,5,5,5,6,7,7,8] and ms [2,4,4,6,4,2,4,4,2,2,4,10,12,4,14]. How can I achieve that? Finally, I would like to be able to save the two lists as plain text files (no commas, no brackets). I tried writeFile+Show, but this saves the lists exactly as printed on screen (whereas I simply would like a text file showing a column of numbers when opened by your favorite editor). Many thanks Lorenzo
On Monday 13 September 2010 00:59:40, Lorenzo Isella wrote:
Dear All, Thanks to the help I got from the list, I was able to (almost) finish a script that performs some data postprocessing (and the code is really amazingly short). Now, there are a few things left. Consider the lists
bs = [4,5,3,1,5,2,7,2,8,2,2,3,3,5,6,7] and ms = [2,2,2,2,4,4,4,4,6,6,4,4,4,10,12,14]
Now, I would like to sort bs (and that is easy) and then (since there is a 1-1 correspondence between the elements in ms and bs) re-order the elements in ms accordingly i.e. bs would become [1,2,2,2,2,3,3,3,4,5,5,5,6,7,7,8] and ms [2,4,4,6,4,2,4,4,2,2,4,10,12,4,14]. How can I achieve that?
import Data.Ord (comparing) import Data.List foo bs ms = unzip . sortBy (comparing fst) $ zip bs ms
Finally, I would like to be able to save the two lists as plain text files (no commas, no brackets). I tried writeFile+Show, but this saves the lists exactly as printed on screen (whereas I simply would like a text file showing a column of numbers when opened by your favorite editor). Many thanks
One list as a column: writeFile "bar" $ unlines (map show list) A list as a space-separated sequence of numbers on one line: writeFile "bar" $ unwords (map show list) If you want to output the list elements in a fixed format (fixed width, right justified; rounded to k decimal places), take a look at Text.Printf. If you want to output several lists as columns side by side, Text.Printf is also what you'd be looking for.
Lorenzo
Finally, I would like to be able to save the two lists as plain text files (no commas, no brackets). I tried writeFile+Show, but this saves the lists exactly as printed on screen (whereas I simply would like a text file showing a column of numbers when opened by your favorite editor). Many thanks
One list as a column:
writeFile "bar" $ unlines (map show list)
A list as a space-separated sequence of numbers on one line:
writeFile "bar" $ unwords (map show list)
Hi Daniel, And thanks for your help. Your solution works, but it looks like that on my machine (an up-to-date desktop computer with plenty of ram) file writing is unusually slow [it looks like it takes more than 10 minutes to write a text file of a few megabites which comes from a long list]. I wonder if there is any way to speed up the process or it is an inherent limitation of lists (or I am making some mistake). Cheers Lorenzo P.S.: the list is a list of lists, hence I use this function save_vector_flat filename list = writeFile filename $ unlines (map show $ concat list)
participants (2)
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Daniel Fischer -
Lorenzo Isella