mjhjmtu

I saw this question How to change the size of nodes? and I wonder:

1. If I want the nodes will be at the same size as automata nodes, what I need to fill at size? (or the scale).


2. If I want make it for all the nodes (I assuming I need to write it at the beginning), what I need to write?

Here is an MWE:

 % Preview source code

%% LyX 2.3.1-1 created this file. For more info, see http://www.lyx.org/.
%% Do not edit unless you really know what you are doing.
documentclass[a4paper,english,hebrew,numbers=noenddot]scrartcl
usepackageamsmath
usepackageamsthm
usepackagefontspec

makeatletter

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% LyX specific LaTeX commands.
pdfpageheightpaperheight
pdfpagewidthpaperwidth


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% User specified LaTeX commands.

usepackagetikz
usetikzlibraryautomata

makeatother

usepackagepolyglossia
setdefaultlanguagehebrew
setotherlanguageenglish
begindocument
begincenter
begintikzpicture
node[state] (1) $1$; 
endtikzpicture
parendcenter

begincenter
begintikzpicture
draw (1,1) node[circle,draw] $1$; 
endtikzpicture
parendcenter
enddocument

Thank you!

I interpret the question slightly different than Phelype. If you want all nodes in that picture to have the same size as the state nodes that come with automata, you only need to say every node/.append style=minimum width=2.5em.

documentclass[tikz,border=3.14mm]standalone
usetikzlibraryautomata
begindocument
begintikzpicture
node[state] (1) $1$; 
endtikzpicture

begintikzpicture[every node/.append style=minimum width=2.5em]
draw (1,1) node[circle,draw] $1$; 
endtikzpicture
enddocument

When you draw a node [state], you are drawing a node [circle,draw,minimum size=2.5em,every state].

How to figure this out:

The usetikzlibrary<library> command loads a tikzlibrary<library>.code.tex file. Searching for the tikzlibraryautomata.code.tex file in my TeX distribution I found it at /usr/local/texlive/2018/texmf-dist/tex/generic/pgf/frontendlayer/tikz/libraries/.

I opened the file and searched for state and found at the end of the file:

tikzstylestate= [state without output]

so state is the same as state without output. Searching for the latter I found:

tikzstylestate without output= [circle,draw,minimum size=2.5em,every state]

thus, state is the same as circle,draw,minimum size=2.5em,every state, with every state being empty by default:

tikzstyleevery state= 

MWE:

documentclassscrartcl
usepackagetikz
usetikzlibraryautomata
begindocument

begincenter
begintikzpicture
node[state] (1) $1$; 
endtikzpicture
endcenter

begincenter
begintikzpicture
draw (1,1) node [circle,draw,minimum size=2.5em,every state] $1$; 
endtikzpicture
endcenter

enddocument

Oh, and answering your second question, you can use more or less the same approach as in the package, but change the every node style. To change it globally you can use tikzset:

tikzset
 every node/.style = 
 circle,draw,minimum size=2.5em,every state
 

or, for a single tikzpicture, you can pass this as an option:

begintikzpicture[
 every node/.style = 
 circle,draw,minimum size=2.5em,every state
 
]
draw (1,1) node $1$; 
endtikzpicture

Here is a minimum example to set the size of state to known value.

documentclass[border=2mm]standalone
usepackagetikz
usetikzlibraryautomata
begindocument
begincenter
begintikzpicture[every state/.style=minimum size=2cm,]
node[state] (1) $1$; 
endtikzpicture

begintikzpicture
draw (1,1) node[circle,draw,minimum size=2cm] $1$; 
endtikzpicture
endcenter
enddocument