\begin{tikzpicture}

  % \fill[red] (0, 0) circle (1pt);
  % \draw (0, 0) --
  % ++(0.375, 0) --
  % ++(60:2) --
  % ++(-0.5, 0) --
  % ++(-120:0.5) --
  % ++(-1.25, 0) --
  % ++(120:0.5) --
  % ++(-0.5, 0) --
  % ++(-60:2) --
  % cycle;

  \begin{scope}
    \foreach \angle in {0, 60, ..., 300} {
      \begin{scope}[rotate = \angle, shift = {(0, 1)}]
        \draw[draw = none, fill = green!40!black]
          (0, 0) --
          ++(0.375, 0) --
          ++(60:2) --
          ++(-0.5, 0) --
          ++(-120:0.5) --
          ++(-1.25, 0) --
          ++(120:0.5) --
          ++(-0.5, 0) --
          ++(-60:2) --
          cycle;
      \end{scope}
    }
  \end{scope}

  \begin{scope}[yshift = 0cm, xshift = 5.5cm, scale = 0.5]

    \foreach \angle in {0, 60, 120} {
      \begin{scope}[rotate = \angle, shift = {(0, 1)}]
        \draw[draw = none, fill = green!40!black]
          (0, 0) --
          ++(0.375, 0) --
          ++(60:2) --
          ++(-0.5, 0) --
          ++(-120:0.5) --
          ++(-1.25, 0) --
          ++(120:0.5) --
          ++(-0.5, 0) --
          ++(-60:2) --
          cycle;
      \end{scope}
    }

    \begin{scope}[xshift = 2cm]
      \foreach \angle in {180, 240, 300} {
        \begin{scope}[rotate = \angle, shift = {(0, 1)}]
          \draw[draw = none, fill = green!40!black]
            (0, 0) --
            ++(0.375, 0) --
            ++(60:2) --
            ++(-0.5, 0) --
            ++(-120:0.5) --
            ++(-1.25, 0) --
            ++(120:0.5) --
            ++(-0.5, 0) --
            ++(-60:2) --
            cycle;
        \end{scope}
      }
    \end{scope}

    \node[color = green!40!black] at (0.75, 0.25) {\huge\it PET};
    \node[color = green!40!black] at (0.95, -0.65) {\it Agronomia};
    \node[color = green!40!black] at (0.2, -1.35) {\it UFGD};

  \end{scope}

\end{tikzpicture}

\begin{tikzpicture}[%
  auto, > = stealth',
  node distance = 0.0ex and 2em,
  pil/.style = {->},
  punkt/.style = {
    rectangle,
    rounded corners = 3pt,
    draw = black,
    text width = 5.5em,
    minimum height = 1.75em,
    text centered}
  ]

\def\tratamentos{Tratamentos}
\def\respostas{Respostas}
\def\covariaveis{Covari{\' a}veis}
\def\rede{Rede de efeitos}

\begin{scope}
  \node[punkt] (y1) {Respostas};
  \node[punkt, above left = of y1] (t1) {\tratamentos};
  \node[punkt, below left = of y1] (x1) {Covari{\' a}veis};
  \path[pil] (t1) edge (y1);
  \path[pil] (x1) edge (y1);
  \node[fit = (t1)(x1)(y1), above, yshift = 1em] (fit1) {Rede de efeitos 1};
\end{scope}

\begin{scope}[xshift = 3.5cm]
  \node[punkt] (t3) {\tratamentos};
  \node[punkt, below right = of t3] (y3) {\respostas};
  \node[punkt, above right = of t3] (x3) {\covariaveis};
  \path[pil] (t3) edge (y3);
  \path[pil] (t3) edge (x3);
  \path[pil, dashed] (x3) edge (y3);
  \node[fit = (t3)(x3)(y3), above, yshift = 1em] (fit3) {\rede{} 2};
\end{scope}

\begin{scope}[xshift = 3.25cm, yshift = -3cm]
  \node[punkt] (y2) {\respostas};
  \node[punkt, left = of y2] (t2) {\tratamentos};
  \node[punkt, below left = 1.75em and -2em of y2] (x2) {\covariaveis};
  \path[pil] (t2) edge (y2);
  \path[pil] (x2) edge (y2);
  \path[pil] (t2) edge (x2);
  \node[fit = (t2)(x2)(y2), above, yshift = 1em] (fit2) {\rede{} 3};
\end{scope}

\end{tikzpicture}%

%% http://tex.stackexchange.com/questions/129571/add-variable-tick-in-axis

\makeatletter
\def\markxof#1{
  \pgf@process{#1}
  \pgfmathparse{
    \pgf@x/\pgfplotsunitxlength+
    \pgfplots@data@scale@trafo@SHIFT@x)/10^\pgfplots@data@scale@trafo@EXPONENT@x}
}
\makeatother

\pgfplotsset{
  every axis/.append style={font=\small},
  mystyle/.style={%
    clip=true,
    axis x line=bottom,
    axis y line=left,
    xmin=1, xmax=64,
    samples =32,
    ymax = 1.6, ymin  = -0.2}
}

\begin{tikzpicture}
  \begin{axis}[
    mystyle,
    grid = major,
    grid style={dashed},
    xlabel={\emph{sample number}},
    xlabel style={at={(1,-0.2)}, anchor=south},
    legend cell align=left,
    legend pos=outer north east]

    \addplot[name path global=one,blue,mark=+,domain=1:64]
      {exp(-log10(2)/(8^2/4)*(\x-32)^2)};
    \addplot[name path global=two,red,domain=1:64] {0.5};
    \path [name intersections={of=one and two, name=i}];
    \pgfplotsextra{
      \path (i-1) \pgfextra{\markxof{i-1}\xdef\mytick{\pgfmathresult}};
    }
    \path let \p1=($(i-1)$) in (\x1,\y1);
    \draw[dashed] (i-1) -- ($(axis cs:0,-0.2)!(i-1)!(axis cs:64,-.2)$);
    \legend{Sampled signal, Threshold}
  \end{axis}

  \begin{axis}[
    mystyle,
    xtick=\empty, ytick=\empty,
    extra x ticks={\mytick},
    extra x tick labels={$t_{step}$},
    extra x tick style={
      xticklabel style={yshift=-10}
    }]
  \end{axis}
\end{tikzpicture} 

\begin{tikzpicture}[%
  auto, > = stealth',
  node distance = 0.0ex and 3em,
  pil/.style = {->},
  punkt/.style = {
    rectangle,
    rounded corners = 3pt,
    draw = black,
    text width = 8em,
    minimum height = 4em,
    text centered}
  ]

\begin{scope}[xshift = 3.5cm]
  \node[punkt, fill = gray!10] (t0) {Aumento da temperatura};
  \node[punkt, fill = gray!10, right = of t0] (t1) {Aumento de banhistas};
  \node[punkt, fill = cyan!30, below right = of t1] (t2) {Aumento das vendas de sorvete ($Y_1$)};
  \node[punkt, fill = orange!30, above right = of t1] (t3) {Aumento dos ataques de tubar{\~a}o ($Y_2$)};
  \path[pil] (t0) edge (t1)
    (t1) edge (t2)
    (t1) edge (t3);
   \path[pil, <->, dashed] (t2) edge (t3);
\end{scope}

\end{tikzpicture}%
kt, below right = of t3] (y3) {\respostas};
  \node[punkt, above right = of t3] (x3) {\covariaveis};
  \path[pil] (t3) edge (y3);
  \path[pil] (t3) edge (x3);
  \path[pil, dashed] (x3) edge (y3);
  \node[fit = (t3)(x3)(y3), above, yshift = 1em] (fit3) {\rede{} 2};
\end{scope}

\begin{scope}[xshift = 3.25cm, yshift = -3cm]
  \node[punkt] (y2) {\respostas};
  \node[punkt, left = of y2] (t2) {\tratamentos};
  \node[punkt, below left = 1.75em and -2em of y2] (x2) {\covariaveis};
  \path[pil] (t2) edge (y2);
  \path[pil] (x2) edge (y2);
  \path[pil] (t2) edge (x2);
  \node[fit = (t2)(x2)(y2), above, yshift = 1em] (fit2) {\rede{} 3};
\end{scope}

\end{tikzpicture}%

%% http://tex.stackexchange.com/questions/69445/using-pgfplots-why-do-i-get-undefined-control-sequence-when-trying-to-use-a-f

\begin{tikzpicture}
  \begin{axis}
    \foreach \x/\y in {a/-1cm, b/0cm, c/1cm} {
      \edef\temp{
        \noexpand\addplot+[
          every error bar/.append style={xshift=\y},
          every node/.style={xshift=\y},
          error bars/y dir=both,
          error bars/y explicit]
      }
      \temp
      coordinates {
        (0, 0) +- (0, 1)
        (1, 0) +- (0, 1)
        (2, 0) +- (0, 1)
      };
    }
  \end{axis}
\end{tikzpicture}

\pgfplotsset{
  select row/.style={
    x filter/.code={\ifnum\coordindex=#1\else\def\pgfmathresult{}\fi}
  }
}

\pgfplotstableread[col sep=comma,header=false]{
  1999/00,167.1
  2000/1,172.5
  2001/2,175
  2002/3,179.3
  2003/4,184.4
  2004/5,188
  2005/6,201.7
  2006/7,208.3
  2007/8,210.2
  2008/9,210.5
  2009/10,209.8
  2010/11,207.5
  2011/12,203.4
  2012/13,198.2
  % 2013/14(YTD),97
}\datatable

\begin{tikzpicture}[scale=0.8]
  \begin{axis}[
    % title=Australia's Primary Energy Consumption by sector - 2012,
    ybar, bar shift=0pt,
    enlarge y limits=0.1,
    % xmin=0,
    xtick={0,...,13},
    xticklabels from table={\datatable}{0},
    ymajorgrids = true,
    bar width=3mm, 
    width=12cm, height=9cm, 
    xlabel={year},
    ylabel={TWh},
    x tick label style={font=\footnotesize,rotate=45, anchor=east},
    nodes near coords align={horizontal}]

    \pgfplotsinvokeforeach{0,...,13}{
      \addplot table [x expr=\coordindex, select row=#1] {\datatable};
    }
    \node[
      pin={[pin distance=1cm, pin edge={<-,>=stealth'},
        shift={(-1.2cm,0.5cm)}]
      Tasmania entry to NEM}] at (axis cs:5,190) {};
  \end{axis}
\end{tikzpicture}

\newcommand{\target}[1]{%
  \foreach \r in {2.5, 2, 1.5, 1, 0.5, 0.05} {
    \draw [
      fill = black,
      fill opacity = 0.05
    ] (0, 0) circle (\r cm);
  }
}%

\begin{tikzpicture}[
  every path/.style = {draw, > = stealth'},
  nodetext/.style = {
    draw, rounded corners = 2pt, fill = white,
  },
  labeltext/.style = {
    draw, minimum width = 5.25cm, minimum height = 1.5em, fill = gray!20,
  }]

\def\dist{5.5};

\begin{scope}[shift = {(0, 0)}, scale = 1.25]

  \target

  \foreach \x/\y in {0.825/1.414, 1.827/0.407, 1.068/0.855, 2.016/0.645, 2.131/-0.294, 0.341/1.3, 1.306/-0.008, 2.035/-0.416, 1.353/0.156, 1.163/1.409} {
    \draw[fill = orange] (\x, \y) circle (2pt);
  }

  \node[text = cyan] (mean) at (1.4065, 0.5468) {$\times$};
  \node[text = magenta] (theta) at (0, 0) {$\times$};

  \path[->] (mean) to[out = 90, in = 180] ++(1, 1) node[nodetext, right] {$\text{E}(\hat{\theta)}$};
  \path[->] (theta) to[out = 90, in = 0] ++(-1, 1) node[nodetext, left] {$\theta$};
  \path[->] (1.163, 1.409) to[out = 90, in = 180] ++(1, 1) node[nodetext, right] {$\hat{\theta}_i$};

  \node[nodetext] at (0, -3) {$\textcolor{magenta}{\text{EQM}(\hat{\theta})} = \textcolor{cyan}{\text{V}(\hat{\theta})} - \textcolor{red}{\text{B}(\hat{\theta})}^2$};

\end{scope}

\begin{scope}[shift = {(7, 0)}]

  \target

  \foreach \x/\y in {0.825/1.414, 1.827/0.407, 1.068/0.855, 2.016/0.645, 2.131/-0.294, 0.341/1.3, 1.306/-0.008, 2.035/-0.416, 1.353/0.156, 1.163/1.409} {
    \draw[fill = orange] (\x, \y) circle (2pt);
    \draw[dashed, magenta] (\x, \y) -- (0, 0);
  }

  \node[nodetext] at (0, -1) {$\textcolor{magenta}{\text{EQM}(\hat{\theta})} = 1/n\sum (\hat{\theta}_i - \theta)^2$};

  \node[text = cyan] at (1.4065, 0.5468) {$\times$};
  \node[text = magenta] at (0, 0) {$\times$};

\end{scope}

\begin{scope}[shift = {(12, 2.75)}]

  \target

  \foreach \x/\y in {0.825/1.414, 1.827/0.407, 1.068/0.855, 2.016/0.645, 2.131/-0.294, 0.341/1.3, 1.306/-0.008, 2.035/-0.416, 1.353/0.156, 1.163/1.409} {
    \draw[fill = orange] (\x, \y) circle (2pt);
    \draw[dashed, cyan] (\x, \y) -- (1.4065, 0.5468);
  }

  \node[nodetext] at (0, -1) {Vari{\^a}ncia: $\textcolor{cyan}{\text{V}(\hat{\theta})} = 1/n\sum (\hat{\theta}_i - \text{E}(\hat{\theta}))^2$};

  \node[text = cyan] at (1.4065, 0.5468) {$\times$};
  \node[text = magenta] at (0, 0) {$\times$};

\end{scope}

\begin{scope}[shift = {(12, -2.75)}]

  \target

  \foreach \x/\y in {0.825/1.414, 1.827/0.407, 1.068/0.855, 2.016/0.645, 2.131/-0.294, 0.341/1.3, 1.306/-0.008, 2.035/-0.416, 1.353/0.156, 1.163/1.409} {
    \draw[fill = orange] (\x, \y) circle (2pt);
  }

  \node[nodetext] at (0, -1) {V{\'i}cio: $\textcolor{red}{\text{B}(\hat{\theta})} = \text{E}(\hat{\theta}) - \theta$};

  \node[text = cyan] at (1.4065, 0.5468) {$\times$};
  \node[text = magenta] at (0, 0) {$\times$};

  \draw[dashed, red] (0, 0) -- (1.4065, 0.5468);

\end{scope}

\end{tikzpicture}%

% # R code.
% set.seed(123)
% n <- 10
% xy <- round(cbind(1.25 + 1 * runif(n, -1, 1),
%                   0.50 + 1 * runif(n, -1, 1)),
%             digits = 3)
% colMeans(xy)
% u <- apply(xy,
%            MARGIN = 1,
%            FUN = function(x) {
%                paste(x, collapse = "/")
%            })
% cat(u, sep = ", ", "\n")

\begin{tikzpicture}[
  every path/.style = {draw, > = stealth'},
  nodetext/.style = {
    rounded corners = 2pt, fill = white, minimum height = 2em
  },
  ]

  \draw (0, 0) -- ++(0, 4) node[nodetext, above] {$\theta$};
  \draw (1.4065, 0) -- ++(0, 4) node[nodetext, above] {$\text{E}(\hat{\theta})$};

  \def\fac{0.38}

  \foreach \x [count = \y] in {0.825, 1.827, 1.068, 2.016, 2.131, 0.341, 1.306, 2.035, 1.353, 1.163} {
    \draw[fill = orange] (\x, \fac*\y) circle (2pt);
    \draw[dashed, yshift =  1pt, magenta] (0, \fac*\y) -- (\x, \fac*\y);
    \draw[dashed, yshift = -1pt, cyan] (1.4065, \fac*\y) -- (\x, \fac*\y);
  }

  \path[->] (2.035, \fac*8) to[out = 90, in = 180] ++(1, 1) node[nodetext, right] {$\hat{\theta}_i$};

  \node[nodetext, right] at (3, 2.5) {
    $\textcolor{magenta}{\text{EQM}(\hat{\theta})} =
    \textcolor{cyan}{\text{V}(\hat{\theta})} - \textcolor{red}{\text{B}(\hat{\theta})}^2$};


  \path[->, yshift = 1pt, magenta] (1.827 - 0.2, \fac*2) to[out = 90, in = 180] (3, 1.2)
    node[nodetext, right, text = black] {
      $\textcolor{magenta}{\text{EQM}(\hat{\theta})} = (1/n) \sum (\hat{\theta}_i - \theta)^2$};

  \path[->, yshift = -1pt, cyan] (1.827 - 0.2, \fac*2) to[out = -90, in = 180] (3, 0.50)
    node[nodetext, right, text = black] {
      Vari{\^a}ncia: $\textcolor{cyan}{\text{V}(\hat{\theta})} =
      (1/n)\sum (\hat{\theta}_i - \text{E}(\hat{\theta}))^2$};

  \draw[dashed, yshift = -4pt, red] (1.4065, 0) -- (0, 0);
  \path[->, red] (1.4065/2, -4pt) to[out = -90, in = 180] (3, -0.3)
    node[nodetext, right, text = black] {
      V{\'i}cio: $\textcolor{red}{\text{B}(\hat{\theta})} = \text{E}(\hat{\theta}) - \theta$};

\end{tikzpicture}%

% # R code.
% set.seed(123)
% n <- 10
% xy <- round(cbind(1.25 + 1 * runif(n, -1, 1),
%                   0.50 + 1 * runif(n, -1, 1)),
%             digits = 3)
% colMeans(xy)
% u <- apply(xy,
%            MARGIN = 1,
%            FUN = function(x) {
%                paste(x, collapse = "/")
%            })
% cat(u, sep = ", ", "\n")

\newcommand{\target}[1]{%
  \foreach \r in {2.5, 2, 1.5, 1, 0.5, 0.05} {
    \draw [
      fill = black,
      fill opacity = 0.15
    ] (0, 0) circle (\r cm);
  }
}%

\newcommand{\points}[3]{%
  \foreach \i in {1, 2, ..., 20} {
    \pgfmathsetmacro{\xcoord}{#1 + rand * #3}
    \pgfmathsetmacro{\ycoord}{#2 + rand * #3}
    \draw[fill = orange] (\xcoord, \ycoord) circle (2pt);
  }
}%


\newcommand{\circlevar}[3]{%
  \draw[color = green] (#1, #2) circle (#3 cm);
  \node[text = green] at (#1, #2) {$\times$};
}%

\def\border{
  \draw (-2.65, -2.75) -- ++(5.25, 0);
  \draw (2.75, 2.65) -- ++(0, -5.25);
}%

\begin{tikzpicture}[
  labeltext/.style = {
    draw, minimum width = 5.25cm, minimum height = 1.5em, fill = gray!20,
  }]

\def\dist{5.5};

\begin{scope}[shift = {(0, 0)}]

  \node[labeltext] at (0, 3) {Sem v{\'i}cio};
  \node[labeltext, rotate = 90] at (-3, 0) {Alta vari{\^a}ncia};
  \target

  \points{0}{0}{1}

  \circlevar{0}{0}{1.15}
  \border
\end{scope}

\begin{scope}[shift = {(\dist, 0)}]

  \node[labeltext] at (0, 3) {Com v{\'i}cio};
  \target 

  \points{1.25}{0.50}{1}

  \circlevar{1.25}{0.50}{1.15}
  \border
\end{scope}

\begin{scope}[shift = {(0, -\dist)}]

  \node[labeltext, rotate = 90] at (-3, 0) {Baixa vari{\^a}ncia};
  \target

  \points{0}{0}{0.5}

  \circlevar{0}{0}{0.65}
  \border
\end{scope}

\begin{scope}[shift = {(\dist, -\dist)}]

  \target

  \points{1.25}{0.5}{0.5}

  \circlevar{1.25}{0.50}{0.65}
  \border
\end{scope}

\end{tikzpicture}%cope}[shift = {(\dist, -\dist)}]

  \target

  \foreach \j in {1, 2, ..., 20} {
    \pgfmathsetmacro{\xcoord}{1.25 + rand * 0.5}
    \pgfmathsetmacro{\ycoord}{0.50 + rand * 0.5}
    \draw[fill = orange] (\xcoord, \ycoord) circle (2pt);
  }

  \circlevar{1.25}{0.50}{0.75}
  \border
\end{scope}

\end{tikzpicture}%scope}[minimum width = 1em, text width = 5.0em, text centered]
% 
%   \node[state] (int) at ( 90:5.5) {\emph{Intui{\c c}{\~ a}o e viabilidade}};
%   \node[state] (val) at (210:5.0) {\emph{Solu{\c c}{\~ a}o e valida{\c c}{\~ a}o}};
%   \node[state] (aut) at (-30:5.0) {\emph{Automa{\c c}{\~ a}o e escala}};
% 
%   \node (con) at (90:3) {Dom{\' i}nio de\\ conhecimento};
%   \node (est) at (210:3) {Matem{\' a}tica \& Estat{\' i}stica};
%   \node[text width = 7em] (hac) at (-30:3) {Habilidades de\\ computa{\c c}{\~ a}o};
% 
%   \node[color = red] (sof) at (30:2) {Processamento tradicional};
%   \node[color = red] (pes) at (150:2) {Pesquisa tradicional};
%   \node[color = red] (mac) at (-90:2) {Zona perigosa};
% 
%   \node (ds) at (0:0) {\large Data Science};
% 
% \end{scope}

% \begin{scope}[
%   every node/.style = {
%     text centered,
%     font = \footnotesize,
%     text width = 5em
%   }]
% 
%   \node at ( 50:3.50) {Engenharia};
%   \node at (130:3.50) {Direito};
%   \node at ( 70:5.00) {Biologia};
%   \node at (110:5.00) {Marketing};
%   \node at ( 60:4.25) {Economia};
%   \node at (120:4.25) {Comunica{\c c}{\~a}o};
%   \node at ( 90:4.25) {Gest{\~a}o};
% 
%   \node at ( 05:4.0) {Programa{\c c}{\~a}o};
%   \node at (-05:4.5) {Algor{\'\i}tmos};
%   \node at (-15:5.0) {Bancos de dados};
%   \node at (-50:3.5) {Computa{\c c}{\~a}o em n{\'u}vem};
%   \node at (-60:4.5) {Machine learning};
% 
%   \node at (175:4.0) {Visualiza{\c c}{\~a}o};
%   \node at (185:4.5) {Otimiza{\c c}{\~a}o};
%   \node at (195:5.0) {Infer{\^e}ncia estat{\'\i}stica};
%   \node at (230:3.5) {An{\'a}lise multivariada};
%   \node at (240:4.5) {Modelagem estat{\'\i}stica};
% 
% \end{scope}

\end{tikzpicture}%%