How to remove leading spaces from the output

Question

In mathematica-output how can one removes the leading spaces from each line of the output.

Here is a sample code

SetDirectory[Directory[]] 
result=(4*(5*y^7*(-1 + 4*z) + y^6*(15 - 83*z + 80*z^2) - 5*z^4*(-2+4*z
 - 3*z^2 + z^3) + y^5*(-20 + 147*z - 273*z^2 + 140*z^3) + y*z^3*(40 
 - 154*z + 147*z^2 - 83*z^3 + 20*z^4) + y^2*z^2*(60 - 254*z + 363*z^2 
 - 273*z^3 + 80*z^4) + y^3*z*(40 - 254*z + 462*z^2 - 439*z^3 + 140*z^4) 
 + y^4*(10 - 154*z + 363*z^2 - 439*z^3 + 160*z^4)) - 9*(y + z)^4*(2  
 + y^2*(3 - 9*z) - 4*z + 3*z^2 - z^3 + y^3*(-1 + 4*z) + y*(-4 + 12*z 
 - 9*z^2 + 4*z^3))*H[0, y] ); 
 result >> output.m;
 Quit[]

where the output is

cat output.m

(4*(5*y^7*(-1 + 4*z) + y^6*(15 - 83*z + 80*z^2) -
    5*z^4*(-2 + 4*z - 3*z^2 + z^3) + y^5*(-20 + 147*z - 273*z^2 + 140*z^3) +
    y*z^3*(40 - 154*z + 147*z^2 - 83*z^3 + 20*z^4) +
    y^2*z^2*(60 - 254*z + 363*z^2 - 273*z^3 + 80*z^4) +
    y^3*z*(40 - 254*z + 462*z^2 - 439*z^3 + 140*z^4) +
    y^4*(10 - 154*z + 363*z^2 - 439*z^3 + 160*z^4)) -
  9*(y + z)^4*(2 + y^2*(3 - 9*z) - 4*z + 3*z^2 - z^3 + y^3*(-1 + 4*z) +
    y*(-4 + 12*z - 9*z^2 + 4*z^3))*H[0, y] )

from the 2nd line of the output there are 4 or 2 spaces in front of each line. For some larger expression this looks worse.
Is there any way to remove those leading spaces in the output in mathematica? Note: This is a question of beautification of the output, nothing wrong with the output, its still right. I just want to remove the leading spaces? Is there any smart way to output so that this problem does not appear?

Answer 1

This is fairly manual in the sense that one has to take charge of where the line breaks are to occur, but it will output a text file with the line breaks aligned on the left.

The strategy is to convert the expression to a string and then make a list of the string where line breaks are set at user specified expressions.

result=(4*(5*y^7*(-1 + 4*z) + y^6*(15 - 83*z + 80*z^2) - 5*z^4*(-2+4*z
 - 3*z^2 + z^3) + y^5*(-20 + 147*z - 273*z^2 + 140*z^3) + y*z^3*(40 
 - 154*z + 147*z^2 - 83*z^3 + 20*z^4) + y^2*z^2*(60 - 254*z + 363*z^2 
 - 273*z^3 + 80*z^4) + y^3*z*(40 - 254*z + 462*z^2 - 439*z^3 + 140*z^4) 
 + y^4*(10 - 154*z + 363*z^2 - 439*z^3 + 160*z^4)) - 9*(y + z)^4*(2  
 + y^2*(3 - 9*z) - 4*z + 3*z^2 - z^3 + y^3*(-1 + 4*z) + y*(-4 + 12*z 
 - 9*z^2 + 4*z^3))*H[0, y] ); 

Convert to a string

resultString = ToString[result, InputForm]

Locate the positions where we have y raised to a power or the multipliers y*z^3 or 9*(y + z)^4.

resultPositions = StringPosition[resultString,
  {"+ y^" ~~ _, "+ y*z^3", "- 9*(y + z)^4*"}]

(* {{21, 25}, {81, 85}, {121, 127}, {170, 174}, {222, 
  226}, {273, 277}, {323, 336}, {340, 344}, {376, 380}} *)

Add the beginning and end to the positions

resultPositions = Join[{{1, 20}}, resultPositions, {{433, 433}}]

Now make a list of the substrings where we want line breaks to occur

resultStringsList = Map[StringTake[resultString,
     {resultPositions[[#, 1]], resultPositions[[# + 1, 1]] - 1}] &, 
      Range[10]]

This is what it looks like in a column

resultStringsList // Column

Export it to a text file

Export["output.m", resultStringsList, "Text"]

The file "output.m" appears similar to the column above.