\documentclass[10pt,a4paper]{article}

% Packages
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%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{blakecromar}
\pdfinfo{
  /Title (python-numpy.pdf)
  /Creator (Cheatography)
  /Author (blakecromar)
  /Subject (Python (Numpy) Cheat Sheet)
}

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% Commands
\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
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% Header and Footer
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\fancyhead{} % Set header to blank
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\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Python (Numpy) Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{blakecromar} via \textcolor{DarkBackground}{\uline{cheatography.com/218070/cs/48258/}}}
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\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}blakecromar \\
  \uline{cheatography.com/blakecromar} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 3rd July, 2026.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
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  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

% Set font size to small. Switch to any value
% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{numpy.ndarray}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{import numpy as np \newline  \newline \# creating arrays \newline arr = np.array({[}1, 2, 3{]})                    \# 1D array, shape (3,) \newline arr = np.array({[}{[}1, 2{]}, {[}3, 4{]}{]})             \# 2D array, shape (2, 2) \newline arr = np.zeros((rows, cols))                 \# 2D array of zeros \newline arr = np.empty((rows, cols, channels))       \# 3D array uninitialized \newline  \newline \# inspecting arrays \newline arr.shape                                    \# dimensions e.g. (480, 640, 3) \newline arr.dtype                                    \# data type e.g. uint8, float32 \newline arr.ndim                                     \# number of dimensions} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{The core data structure in NumPy — a multi-dimensional array of elements all of the same type. \newline More efficient than Python lists for numerical data as elements are stored contiguously in memory. \newline Shape describes the dimensions — (rows, cols) for 2D, (rows, cols, channels) for 3D.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{numpy.dtype}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{import numpy as np \newline  \newline \# common dtypes \newline np.dtype(np.uint8)    \# unsigned 8-bit integer  (0 to 255) \newline np.dtype(np.int8)     \# signed 8-bit integer    (-128 to 127) \newline np.dtype(np.uint16)   \# unsigned 16-bit integer (0 to 65535) \newline np.dtype(np.int16)    \# signed 16-bit integer   (-32768 to 32767) \newline np.dtype(np.int32)    \# signed 32-bit integer \newline np.dtype(np.float32)  \# 32-bit floating point \newline np.dtype(np.float64)  \# 64-bit floating point \newline  \newline \# checking dtype \newline arr = np.array({[}1, 2, 3{]}, dtype=np.float32) \newline arr.dtype             \# float32 \newline arr.itemsize          \# bytes per element → 4} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Describes the data type of elements stored in a numpy.ndarray. \newline Common types are uint8 for images (0-255), float32 for floating point, and int32 for integers. \newline The dtype determines how many bytes each element takes and how values are interpreted.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{numpy.uint8}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{import numpy as np \newline  \newline arr = np.array({[}0, 128, 255{]}, dtype=np.uint8)  \# valid values \newline arr.dtype      \# uint8 \newline arr.itemsize   \# 1 byte per element \newline  \newline \# wrapping behaviour — values overflow silently \newline np.uint8(255) + np.uint8(1)   \# returns 0, not 256 \newline  \newline \# common usage — converting to uint8 for image saving \newline arr = np.clip(arr, 0, 255).astype(np.uint8)   \# safe conversion} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{An unsigned 8-bit integer type commonly used for image data. \newline Can hold values from 0 to 255 — exactly the range of a single colour channel in an image. \newline Values that exceed 255 wrap around rather than raising an error — a common source of bugs.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}