Graphics, Figures & Tables ⇒ TiKz (\foreach): reversing arrows

[Sundial]

The upper group of triangle shaped arrows should be reversed until nullifying the one on the top, in order to have the column antisymmetrically loaded. Thanks in advance.
Solved what said in next note, figure just uploaded:
----------------
PS: unable to attach the suitable screenshot. Why not allowed by the forum platform? A figure is often better than thousands of words!
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Code: Select all

\documentclass{article}
\usepackage{tikz}            
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{center}
\setlength\PreviewBorder{10pt}

\tikzstyle{axis}   = [-latex,blue!55]

\tikzstyle{two}=[x={(0.75cm,0cm)},y={(0cm,0.75cm)}]

\begin{document}
\begin{center}
  \begin{tikzpicture}[two]
        \coordinate (O) at (0,0);
        \draw[axis] (O) -- ++(4,0) node[right] {$x$};
        \draw[axis] (O) -- ++(0,6) node[above] {$y$};
        
% --- 1 ----
    \foreach \y in {0.5,0.75,...,2.5} { % 1st triangle shaped arrows
      \draw[-latex] (-1*\y/2.5,\y) -- (0,\y);
    }
% --- 2 ----    
    \foreach \y in {2.5,2.75,...,5} { % (trouble) 2nd triangle shaped arrows
      \draw[-latex] (1*\y/2.5,\y) -- (0,\y);
    }    

  \end{tikzpicture} 
\end{center}
\end{document}
%

[Stefan Kottwitz]

unable to attach the suitable screenshot. Why not allowed by the forum platform? A figure is often better than thousands of words!

It is allowed. What did you try? Use some words to explain what you did for attaching, because jpg and png and such are allowed and I cannot guess what you tried.

Stefan

[Sundial]

Simply said, Stefan. Both tags Img and URL need to catch images from external links[http://...bla,bla,bla], not from the user's computer (mine, I mean, where the screenshot is located), as it happens in many similar platforms in the world! Cheers

[Stefan Kottwitz]

Both tags Img and URL need to catch images from external links

Sure, those are links. But you said attach, and we definitely support attachments. Click on "Upload attachment" below the post edit field.

Stefan

[Sundial]

Thank you, Stefan! The solution of my troubles was ... under my nose! Figure properly att'd in the opening post. Cheers

[Sundial]

One more latex code, just to show a manually (and deprecated) way to draw upper arrows. Awaiting for the wished drift. Thx&Cheers

Code: Select all

\documentclass{article}
\usepackage{tikz} 
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{center}
\setlength\PreviewBorder{10pt}

\tikzstyle{axis} = [-latex,blue!55]

\tikzstyle{two}=[x={(0.75cm,0cm)},y={(0cm,0.75cm)}]

\begin{document}
\begin{center}
\begin{tikzpicture}[two]
\coordinate (O) at (0,0);
\draw[axis] (O) -- ++(4,0) node[right] {$x$};
\draw[axis] (O) -- ++(0,6) node[above] {$y$};

% --- 1 ----
\foreach \y in {0.5,0.75,...,2.5} { % 1st triangle shaped arrows
\draw[-latex] (-1*\y/2.5,\y) -- (0,\y);
}

% --- 2 ---- 
%\foreach \y in {2.5,2.75,...,5} { % (trouble) 2nd triangle shaped arrows
%\draw (1*\y/2.5,\y) -- (0,\y);
%}
% -------- Deprecated: manually drawing of upper arrows -----------
%                      ... just to show what I'm looking for -------
\draw[-latex] (1,2.5) -- (0,2.5);
\draw[-latex] (0.9,2.75) -- (0,2.75);
\draw[-latex] (0.8,3) -- (0,3); 
\draw[-latex] (0.7,3.25) -- (0,3.25); 
\draw[-latex] (0.6,3.5) -- (0,3.5); 
\draw[-latex] (0.5,3.75) -- (0,3.75); 
\draw[-latex] (0.4,4) -- (0,4); 
\draw[-latex] (0.3,4.25) -- (0,4.25); 
\draw[-latex] (0.2,4.5) -- (0,4.5); 
%\draw[-latex] (0.05,4.75) -- (0,4.75); 
%\draw[-latex] (0,5) -- (0,5); % zero lenght arrow
% ----------------------------------------------------------------------
%
% Contours
\draw [blue] (0,0) -- (-1,2.5); % closing queues lower arrows
\draw [red] (0,5) -- (1,2.5); % closing queues upper arrows

\end{tikzpicture} 
\end{center}
\end{document}

[Stefan Kottwitz]

I see! So you just need the correct math calculation of the x coordinate. Use this:

Code: Select all

\foreach \y in {2.5,2.75,...,4.5} {
  \draw[-latex] (2-\y/2.5,\y) -- (0,\y);}

arrows.png (8.59 KiB) Viewed 7174 times

It's like x=(5-y)/2.5.

Stefan

[Sundial]

So good, Stefan! Now the code works properly. The \foreach command has a really strong powerfulness, so I should study it for several applications in structural engineering. Thank you very much and best wishes.

[Johannes_B]

Structural engineering? You might be interested in TikZ Library for Structural Analysis.

[Sundial]

Structural engineering? You might be interested in TikZ Library for Structural Analysis.

Hi Johannes, I've faced that lib a couple of years ago, without satisfaction, unfortunately! Plenty of commands to learn and great difficulty to draw simple load schemes as the above, just solved. This is, of course, my opinion. Please, stay tuned to look at my next post. Cheers