[Tex/LaTex] Centering text in TikZ tree node

horizontal alignmentnodestikz-pgf

I'd like to have my text inside TikZ tree nodes centered; below is my progress so far:

\documentclass[10pt, a4paper]{article}   
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}

\tikzset{
  treenode/.style = {align=center, inner sep=1pt, text centered,
  font=\sffamily},
  arn_m/.style = {treenode, rectangle, rounded corners=1mm, text centered, white,
  font=\sffamily\bfseries, draw=black, fill=black, text width=7em},
  arn_n/.style = {treenode, rectangle, white, font=\sffamily\bfseries, 
  draw=black, fill=black, text width=2em},
  arn_r/.style = {treenode, rectangle, red, draw=red, 
  text width=3em, very thick},
  arn_x/.style = {treenode, rectangle, draw=black,
  minimum width=0.5em, minimum height=0.5em}
}

\begin{center}

\begin{tikzpicture}[->,>=stealth',level/.style={sibling distance = 5cm/#1,
  level distance = 1cm}] 
\node [arn_m] {2 3 6 5 7}
    child{ node [arn_r] {15 2} 
            child{ node [arn_n] {10} 
                child{ node [arn_r] {5} edge from parent node[above left]
                         {$x$}} %for a named pointer
                            child{ node [arn_x] {}}
            }
            child{ node [arn_n] {20}
                            child{ node [arn_r] {18}}
                            child{ node [arn_x] {}}
            }                            
    }
    child{ node [arn_r] {47}
            child{ node [arn_n] {38} 
                            child{ node [arn_r] {36}}
                            child{ node [arn_r] {39}}
            }
            child{ node [arn_n] {51}
                            child{ node [arn_r] {49}}
                            child{ node [arn_x] {}}
            }
        }
; 
\end{tikzpicture}

\end{center}
\end{document}

As you can see the text in the nodes is not centered properly as it is biased to the right and normal fixing techniques (like putting text centered and so on) do not resolve the problem. Could someone provide me a tip on how to align the node text properly?

Best Answer

The culprit seems to be text width. If you change it to minimum width, then the texts will be centered properly.

Code

\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\tikzset{
  treenode/.style = {align=center, inner sep=1pt,
  font=\sffamily},
  arn_m/.style = {treenode, rectangle, rounded corners=1mm, white,
  font=\sffamily\bfseries, draw=black, fill=black, minimum width=7em},
  arn_n/.style = {treenode, rectangle, white, font=\sffamily\bfseries, 
  draw=black, fill=black, minimum width=2em},
  arn_r/.style = {treenode, rectangle, red, draw=red, 
  minimum width=3em, very thick},
  arn_x/.style = {treenode, rectangle, draw=black,
  minimum width=0.5em, minimum height=0.5em}
}
\begin{tikzpicture}[->,>=stealth',level/.style={sibling distance = 5cm/#1,
  level distance = 1cm}] 
\node [arn_m] {2 3 6 5 7}
    child{ node [arn_r] {15 2} 
            child{ node [arn_n] {10} 
                child{ node [arn_r] {5} edge from parent node[above left]
                         {$x$}} %for a named pointer
                            child{ node [arn_x] {}}
            }
            child{ node [arn_n] {20}
                            child{ node [arn_r] {18}}
                            child{ node [arn_x] {}}
            }                            
    }
    child{ node [arn_r] {47}
            child{ node [arn_n] {38} 
                            child{ node [arn_r] {36}}
                            child{ node [arn_r] {39}}
            }
            child{ node [arn_n] {51}
                            child{ node [arn_r] {49}}
                            child{ node [arn_x] {}}
            }
        }
; 
\end{tikzpicture}
\end{document}

Output

enter image description here

Comments

text centered may be a deprecated option; I couldn't find it anywhere in the TikZ documentation
As Alan Munn says in his comment, please help us help you by posting a compilable MWE in the future.

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Near the end of the first scope,

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does the same. Additionally (near the end of the second scope),

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[Tex/LaTex] How to define the default vertical distance between nodes

I don't really get the question so I hope this is what you wanted. If you include a full document (such that we copy paste and see the problem on our systems) things are much more easier.

Here, you can change the default setting within a scope but your block style had a node distance which was resetting every time it is issued. I've made it 2mm such that we can see the difference easier.

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,shapes.geometric,positioning}

\begin{document}
\begin{tikzpicture}[decision/.style={diamond, draw, text width=4.5em, text badly centered, node distance=3.5cm, inner sep=0pt},
                    block/.style   ={rectangle, draw, text width=6em, text centered, rounded corners, minimum height=4em, minimum height=2em},
                    cloud/.style   ={draw, ellipse, minimum height=2em},
                    line/.style    ={draw,-latex'},
                    node distance = 1cm, 
                    auto]
    \node [block] (1st) {1st};
    \node [block, right= of 1st]  (2nd1) {2nd1};
\begin{scope}[node distance=2mm and 10mm]%Here we change it for everything inside this scope
    \node [block, above= of 2nd1] (2nd2) {2nd2};
    \node [block, below= of 2nd1] (2nd3) {2nd3};
    \node [block, right= of 2nd1] (3rd1) {3rd1};
    \node [block, above= of 3rd1] (3rd2) {3rd2};
    \node [block, above= of 3rd2] (3rd3) {3rd3};
\end{scope}
    \node [block, below= of 3rd1] (3rd4) {3rd4};
    \node [block, below= of 3rd4] (3rd5) {3rd5};

    \path [line] (1st) -- (2nd1);
    \path [line] (2nd1) -- (2nd2);
    \path [line] (2nd1) -- (2nd3);
    \path [line] (2nd2) -- (3rd3);
    \path [line] (2nd1) -- (3rd1);
    \path [line] (1st) -- (2nd1);
\end{tikzpicture}
\end{document}