documentclass[a4paper]{article}

usepackage{tikz}
usepackage{pgfplots}
pgfplotsset{compat=1.11}
usepgfplotslibrary{fillbetween}
usetikzlibrary{
  arrows,
  decorations,
  calc,
  intersections,
  matrix,
  decorations.pathmorphing,
  spy,
}

newcommandsignplot[4]{ % start end points signStart
  % Draws a line between #1 and #2
  draw[shorten <= -1cm, shorten >= -1cm] (#1) -- (#2);

  % Checking whether the first sign is positive or not
  ifnum1=#4relax % It starts positive
    % Cycle between the list of points given at which the sign changes
    foreach x in #3{
      % Drawing circles with the text
      coordinate (A) at (#1);
      coordinate (B) at (x,0);
      filldraw[fill=black,draw=black] (A-|B) circle(2pt)
        node[below]{x};
      % Going through 0->x (where x = current coordinate) with a step of 0.3
      foreach c in {0,0.3,0.6,...,x}{
        coordinate (A1) at ($(A)+(-1cm,0)$);
        % Drawing the + sign above the line
        coordinate (C) at ($(A1-|B)+(0,0.2)$);
        coordinate (D) at (c,0);
        node at (C-|D) {+};
      }
    }
  else % Same as above
    foreach x in #3{
      coordinate (A) at (#1);
      coordinate (B) at (x,0);
      filldraw[fill=black,draw=black] (A-|B) circle(2pt)
        node[below]{x};
      foreach c in {0.3,0.6,...,x}{
        % Just drawing the - sign below
        coordinate (C) at ($(A-|B)+(0,-0.2)$);
        coordinate (D) at (c,0);
        node at (C-|D) {-};
      }
    }
  fi
}

begin{document}
    begin{tikzpicture}
        coordinate (O) at (0,0);
        coordinate (A) at (5,0);
        signplot{O}{A}{{0,3}}{0}
    end{tikzpicture}
end{document}