How to adjust the legend line length in pgfplots

Question

I have a plot using pgfplots but I need to adjust the length of each legend. I can modify the width of each legend line, but I don't know how to modify the length of them. Is there any option to change that?

\documentclass[10pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\begin{document}
            \begin{tikzpicture}
                \begin{axis}
                    [
                       legend style={font=\tiny, draw=none, style={at={(0.6,1)}}, row sep=-0.12cm, inner sep=0pt, line width=0.5pt,}, %is there any line length??
                       legend entries={A1, A2, A3, A4 A5, A6, A7},
                       legend columns=2,
                    ]
                    \addplot coordinates {
                        (5,-4864175164880)
                        (10,-9728350329760)
                        (15,-14592525494640)
                        (20,-19456700659520)
                        (25,-24320875824400)
                        (30,-29185050989280)
                        (35,-34049226154160)
                        (40,-38913401319040)
                        (45,-43777576483920)
                        (50,-48641751648800)
                    };
                    \addplot coordinates {
                        (5,292862229381084)
                        (10,434852463631792)
                        (15,570475846800798)
                        (20,737825490819198)
                        (25,860718238823815)
                        (30,940754521446225)
                        (35,1062038363787050)
                        (40,1127781160335236)
                        (45,1185587487293437)
                        (50,1237044668474952)
                    };
                    \addplot coordinates {
                        (5,302387809568514)
                        (10,433265146600492)
                        (15,568888291277459)
                        (20,745760136185414)
                        (25,863891556048562)
                        (30,1018505467376564)
                        (35,1114397529527600)
                        (40,1243595912571978)
                        (45,1356917686795978)
                        (50,1438505671531397)
                    };
                    \addplot coordinates {
                        (5,292862229381084)
                        (10,439615017666611)
                        (15,579999984864317)
                        (20,680689964623044)
                        (25,830567187638336)
                        (30,989945779779292)
                        (35,1089013026329017)
                        (40,1192831304307391)
                        (45,1218906437648680)
                        (50,1308435574928259)
                    };
                    \addplot coordinates {
                        (5,302387809568514)
                        (10,447552145712824)
                        (15,632378624837750)
                        (20,758456796364679)
                        (25,905150488169182)
                        (30,1039132937342017)
                        (35,1177859366612789)
                        (40,1267392254011344)
                        (45,1393401240771311)
                        (50,1495605989719142)
                    };
                    \addplot coordinates {
                        (5,292862229381084)
                        (10,434852463631792)
                        (15,570475846800798)
                        (20,737825490819198)
                        (25,860718238823815)
                        (30,940754521446225)
                        (35,1062038363787050)
                        (40,1142060277409340)
                        (45,1187173821398126)
                        (50,1260840969614604)
                    };
                    \addplot coordinates {
                        (5,312696217497890)
                        (10,565002605927478)
                        (15,857723287379634)
                        (20,1129748942677279)
                        (25,1334295395262765)
                        (30,1579251153778012)
                        (35,1767865804266326)
                        (40,1996881068279606)
                        (45,2225851981990703)
                        (50,2401688802214620)
                    };
                \end{axis}
            \end{tikzpicture}           
\end{document}

Answer 1

Add these to your code.

\pgfplotsset{
compat=1.11,
legend image code/.code={
\draw[mark repeat=2,mark phase=2]
plot coordinates {
(0cm,0cm)
(0.15cm,0cm)        %% default is (0.3cm,0cm)
(0.3cm,0cm)         %% default is (0.6cm,0cm)
};%
}
}

Change the values as you wish.