mjhjmtu

What is the best way to create diagrams like these in LaTeX? Is Tikz the way to go?

(Code for these specific instances would be useful but is not absolutely required, since I'll be needing to make diagrams similar in spirit but not identical. Also, this has almost certainly been asked before, so I would equally appreciate a link to a previous asking -- I'm just unsure what terms to search to find such a post.)

edit: looked at some old code and came up with

begintikzpicture

draw[ultra thick,domain=0:1,samples=100, postaction=decorate, decoration=markings, mark=at position 0.5 with arrowstealth] (0,1) -- (0,0);
draw[ultra thick,domain=0:1,samples=100, postaction=decorate, decoration=markings, mark=at position 0.5 with arrowstealth] (1,1) -- (0,1);
draw[ultra thick,domain=0:1,samples=100, postaction=decorate, decoration=markings, mark=at position 0.5 with arrowstealth] (1,0) -- (1,1);
draw[ultra thick,domain=0:1,samples=100, postaction=decorate, decoration=markings, mark=at position 0.5 with arrowstealth] (0,0) -- (1,0);

node at (.5,-.2) $a$;

endtikzpicture

although this seems rather clunky.

Welcome to TeX.SE! This answer makes use of this answer.

documentclass[tikz,border=3.14mm]standalone
usetikzlibrarydecorations.markings

begindocument
tikzsetlab dis/.store in=LabDis,
lab dis=0.3,
->-/.style args=at #1 with label #2decoration=
 markings,
 mark=at position #1 with arrow>; node at (0,LabDis) #2;,postaction=decorate,
 -<-/.style args=at #1 with label #2decoration=
 markings,
 mark=at position #1 with arrow<; node at (0,LabDis)
 #2;,postaction=decorate,
 -*-/.style=decoration=
 markings,
 mark=at position #1 with fill (0,0) circle (1.5pt);,postaction=decorate,
 

begintikzpicture[>=latex]
 draw[->-=at 0.125 with label $b$,
 ->-=at 0.375 with label $a$,
 -<-=at 0.625 with label $b$,
 -<-=at 0.875 with label $a$] (0,0) rectangle (4,4);

 draw[lab dis=-0.3,
 -*-=0,->-=at 0.125 with label $b$,
 -*-=0.25,->-=at 0.375 with label $a$,
 -*-=0.5,-<-=at 0.625 with label $b$,
 -*-=0.75,-<-=at 0.875 with label $a$] (2,-4) circle (2.5);
endtikzpicture
enddocument

You can place nodes on a path which should simplify the node positioning a lot. You might also want to factor out the arrow business into a style.

documentclassarticle
usepackagetikz
usetikzlibrarydecorations.markings
begindocument

begintikzpicture[
 arrow inside/.style = 
 postaction=decorate,
 decoration=markings, mark=at position 0.5 with arrowstealth
 
 ]

 draw[arrow inside] (0,0) -- node [below] $a$ (1,0);
 draw[arrow inside] (0,1) -- node [above] $a$ (1,1);
 draw[arrow inside] (0,0) -- node [left] $b$ (0,1);
 draw[arrow inside] (1,0) -- node [left] $b$ (1,1);

endtikzpicture

enddocument

This can be an option

documentclass[tikz, border = 10pt]standalone

usepackagepgfplots
pgfplotssetcompat=newest
usetikzlibrarydecorations.markings

defnframes30
defframe0

begindocument

foreach frame in 0,0,0,0,1,...,nframes


pgfmathsetmacrotimeframe / nframes
pgfmathsetmacroc20 + (3 - 20) / (1 + exp(-10 * (time - 0.6)))
pgfmathsetmacroa20 + (1 - 20) / (1 + exp(-8 * (time - 0.3)))
pgfmathsetmacroxrange3 + (180 - 3) / (1 + exp(-14 * (time - 0.6)))
pgfmathsetmacroyrange3 + (180 - 3) / (1 + exp(-10 * (time - 0.3)))
pgfmathsetmacrotheta90 + (45 - 90) * time
pgfmathsetmacrophi0 + (25 - 0) * time

pgfplotsset
 border one/.style=
 thick,
 red,
 samples y = 0,
 variable = t,
 domain = -xrange:xrange,
 postaction = decorate,
 decoration = markings,
 mark = at position 0.48 with arrowstealth,
 mark = at position 0.52 with arrowstealth
 ,
 border two/.style=
 thick,
 green,
 samples y = 0,
 variable = t,
 domain = -yrange:yrange,
 postaction = decorate,
 decoration = markings, mark = at position 0.5 with arrowstealth
 




begintikzpicture
useasboundingbox (0, 0) rectangle (6, 6);
beginaxis [
 hide axis,
 view = thetaphi,
 domain = -xrange:xrange,
 y domain = -yrange:yrange,
 samples = 20,
 samples y = 20,
 unit vector ratio = 1 1 1,
 declare function = 
 u(x,y) = (c + a * cos(y)) * cos(x);
 v(x,y) = (c + a * cos(y)) * sin(x);
 w(x,y) = a * sin(y);
 
 ]

 addplot3 [
 surf,
 color = blue,
 opacity = 0.01,
 faceted color = white,
 z buffer = sort,
 fill opacity = 0.5] (u(x, y), v(x, y), w(x, y));

 addplot3 [border one] (u(t, yrange), v(t, yrange), w(t, yrange));
 addplot3 [border one] (u(t, -yrange), v(t, -yrange), w(t, -yrange));
 addplot3 [border two] (u(xrange, t), v(xrange, t), w(xrange, t));
 addplot3 [border two] (u(-xrange, t), v(-xrange, t), w(-xrange, t));


endaxis
endtikzpicture

enddocument

DISCLAIMER Just a fun animation, I'm aware it is not exactly what the OP asked for

A PSTricks solution just for fun purposes.

documentclass[pstricks,12pt]standalone
usepackagepstricks-add

begindocument
pspicture[arrowinset=0,arrowscale=2](-4,-4)(4,4)
 curvepnodes[plotpoints=5]03603.5 t 45 add PtoCI
 foreach i/l/a in 0/a/<,1/b/<,2/a/>,3/b/>%
 pcline[ArrowInside=-a](Ii)(Ithenumexpri+1)nbput$l$
endpspicture
pspicture[arrowinset=0,arrowscale=2](-4,-4)(4,4)
 pnode(0,0)O
 curvepnodes[plotpoints=5]03603.5 t 135 add PtoCI
 foreach i/l in 0/a,1/b,2/a,3/b%
 qdisk([nodesep=3.5,angle=-45]IiO)2pt
 psarc->(0,0)3.5(Ii)(Ithenumexpri+1)
 uput8pt[(Ii)](>Ii)$l$
endpspicture
enddocument

Note: ArrowInside is not available for psarc. I don't know why.

Another alternative approach using Metapost. Compile this one with lualatex.

documentclass[border=5mm]standalone
usepackageluatex85
usepackageluamplib
begindocument
mplibtextextlabelenable
beginmplibcode
beginfig(1);
 path S, C;

 S = unitsquare shifted -(1/2, 1/2) scaled 100;
 C = fullcircle scaled 84 rotated 16 shifted 140 right;

 interim ahangle := 30; % slimmer arrows...

 drawarrow subpath(0, 5/8) of S;
 drawarrow subpath(5/8, 13/8) of S;
 drawarrow subpath(4, 4-5/8) of S;
 drawarrow subpath(4-5/8, 4-13/8) of S;
 draw subpath(13/8, 4-13/8) of S;

 label.top("$a$", point 1/2 of S);
 label.top("$a$", point 5/2 of S);
 label.lft("$b$", point 3/2 of S);
 label.lft("$b$", point 7/2 of S);

 for t=0 upto 3:
 drawarrow subpath 2(t, t+1) of C;
 drawdot point 2t+3/4 of C withpen pencircle scaled 3;
 label(if odd t: "$b$" else: "$a$" fi, 9/8[center C, point 2t+7/4 of C]);
 endfor

endfig;
endmplibcode
enddocument