How do I change the arrow length in a tikz file

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Edit:
I have the following code in which I want to change the length of arrows:
documentclass[preview,border=2pt,2pt]{standalone}

usepackage{tikz}
usetikzlibrary{shapes,backgrounds}
usetikzlibrary{calc}
usetikzlibrary{decorations.shapes}
usetikzlibrary{arrows.meta}
tikzset{decorate sep/.style 2 args=
    {decorate,decoration={shape backgrounds,shape=circle,shape size=#1,shape sep=#2}}}
tikzset{>={Latex[width=1mm,length=3mm]}}

begin{document}
    begin{tikzpicture}
    tikzstyle{line} = [line width=.4pt]
    tikzstyle{line1} = [->,line width=.2pt]
    
    defr{0.5pt} %define the radius of spot
    defax{10.2} %define the length of x-axis
    defay{4} %define the length of y-axis
    defx{9} %define the length of x
    defy{3} %define the height of T=1
    defz{0.7} %define the height between the arrow and label
        
    draw[arrows=<->,line width=0.6pt]
    (0,ay) coordinate node [below left] {$T$} -- (0,0) coordinate node[below] {$0$} -- (ax, 0) coordinate node [below left] {$x$};

draw[line] (0,y) -- (2,y) -- (4,0);
    draw[line] (2,0) -- (4,y) -- (5,y) -- (7,0);
    draw[line] (5,0) -- (7,y) -- (x,y);
    draw[densely dotted] (x,y) -- (x,0);
    
    node[below] at (2,0) {$1.6$};
    node[below] at (4,0) {$1.7$};
    node[below] at (5,0) {$1.75$};
    node[below] at (7,0) {$1.85$};
    node[below] at (x,0) {$2$};

node[left] at (0,y) {$1$};
    node[left] at (0,y/2) {$0.5$};
    
    draw[line1] (1.2, y+z) -- (1,y);
        node[above] at (1.2, y+z) {$short$};
    draw[line1] (4.7, y+z) -- (4.5,y);
        node[above] at (4.7, y+z) {$medium$};
    draw[line1] (8.2, y+z) -- (8,y);
        node[above] at (8.2, y+z) {$tall$};
    
    end{tikzpicture}
end{document}

I want to change length of arrows at the last three lines, e.g. "draw[line1] (1.2, y+z) -- (1,y)...", but I am not sure how to do it and need help. Thanks.

Zarko · Answer

Like this?

Instead arrows are used modified pin in nodes placed on path of fuzzy functions. By this the diagram code is much shorter:
documentclass[preview,border=2pt,2pt]{standalone}
usepackage{tikz}
usetikzlibrary{arrows.meta}

begin{document}
    begin{tikzpicture}[
aligned pin/.style args = {[#1]#2:#3}% based on https://tex.stackexchange.com/questions/367130
    {pin={[pin edge={{Straight Barb[angle=60:2pt 3]}-,
                     semithick, draw=black, shorten <=2pt},%
           coordinate,
           label={[%
                append after command={%
                node[inner sep=0pt, outer sep=0pt,%font=...
                     at=(tikzlastnode.#2),%
                     anchor=#1,%
                    ]{#3}%
                }%
            ]center:{}}%
         ]#2:{}}%
    },
          pin distance = 7mm,
            lbl/.style = {inner sep=0pt, 
                          aligned pin={[south west,xshift=-1ex]60:#1}},
           line/.style = {},
                        ]
    defr{0.5pt} %define the radius of spot
    defax{10.2} %define the length of x-axis
    defay{4} %define the length of y-axis
    defx{9} %define the length of x
    defy{3} %define the height of T=1
    defz{0.7} %define the height between the arrow and label
% axis
    draw[arrows=<->,line width=0.6pt]
    (0,ay) coordinate node [below left] {$T$} -- (0,0)   node[below] {$0$} 
                                               -- (ax,0) node[below left] {$x$};
% fuzzy functions
draw[line width=.4pt] 
    (0,y) -- node[lbl=short] {} (2,y) -- (4,0) node[below] {1.7}
    (2,0) node[below] {1.6}   -- (4,y) -- node[lbl=medium] {} (5,y)
                              -- (7, 0) node[below] {1.85}
    (5,0) node[below] {1.75}  -- (7,y) -- node[lbl=tall] {} (x,y);
draw[densely dotted] (x,y) -- (x,0) node[below] {2};

node[left] at (0,y) {$1$};
    node[left] at (0,y/2) {$0.5$};
    end{tikzpicture}
end{document}

Zarko · Answer

Principle to draw shorter line as are follows from given coordinates is use the option shorten > = <amount> (to make arrows shorten on destination coordinate) and shorten < = <amount> (to make it shorted on the start coordinate). For illustration serve the following example:

documentclass[preview,border=2pt,2pt]{standalone}
usepackage{tikz}
usetikzlibrary{arrows.meta}

begin{document}
    begin{tikzpicture}
draw[shorten > = 1cm, -Straight Barb]      
            (0,0) -- (2,0); 
draw[red]  (0,0.2) -- (2,0.2);   
    end{tikzpicture}
end{document}

This concept you can use at arrow of your choice (i.e. at last three arrows as I use in my first answer, where instead separated explicit drawn arrows and nodes above them are used pin which is in its style definition shortened for 2pt).

How do I change the arrow length in a tikz file

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