TikZ is a drawing language for LaTeX that can produce all sorts of diagrams, including commutative diagrams with the tikz-cd package, which is possibly the best package for commutative diagrams, at least with regards to typesetting quality and usability. Sometimes when you draw a diagram, though, you might want a little more programming language thrown in to make drawing easier. A classic example is a timeline. Though probably not useful for research math papers, a timeline could be helpful for a survey paper or history text.
Suppose you have a tab-delimited text file of dates of birthdays:
1809-02-12 Charles Darwin 1822-12-27 Louis Pasteur 1826-09-17 Bernhard Riemann 1877-02-07 Godfrey Harold Hardy 1845-03-03 Georg Cantor
You could draw them on a timeline in TikZ directly, but the problem is you'd have to worry about manually calculating how far down the line these dates are. This is a good case where writing a program in Python 3 that outputs the TikZ picture drawing commands is much easier and painless, especially if you need several timelines:
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#!/usr/bin/python3 import datetime import re from sys import argv #Constants monthNames = ["January", "Feburary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"] #Data dates = [] description = [] lengthOfLine = 10 #Input of the form string "yyyy-mm-dd" def dashedToDate(dashed): dateArray = dashed.split('-') year = int(dateArray[0]) month = int(dateArray[1]) day = int(dateArray[2]) return datetime.date(year,month,day) if len(argv) > 1: data = open(argv[1],'r') else: data = open('dates.txt', 'r') while True: line = data.readline() if not line: break entry = line.split('\t') dates.append(dashedToDate(entry[0])) description.append(re.sub("\n","",entry[1])) data.close() # create file to put the TeX/Tikz code texfile = open('picture.tex','w') texfile.writelines("\\begin{tikzpicture}") # Styles used texfile.writelines("[datemarker/.style={circle,draw=black,fill=white,radius=4pt},\n") texfile.writelines("textlabel/.style={anchor=west,text height=1.7ex,text depth=.25ex}]\n") # Draw the background texfile.writelines("\\draw (0,0) -- (0,"+ str(lengthOfLine)+ ");\n") startDate = dates[0] endDate = dates[0] for x in range(len(dates)): if dates[x] < startDate: startDate = dates[x] if dates[x] > endDate: endDate = dates[x] span = (endDate - startDate).days # Draw the dates for x in range(len(dates)): diff = (dates[x] - startDate).days month = monthNames[dates[x].month-1] dateText = month+" "+str(dates[x].day)+", "+str(dates[x].year) yCoordOnLine = lengthOfLine - (diff/span)*lengthOfLine#!/usr/bin/python3 import datetime import re from sys import argv #Constants monthNames = ["January", "Feburary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"] #Data dates = [] description = [] lengthOfLine = 10 #Input of the form string "yyyy-mm-dd" def dashedToDate(dashed): dateArray = dashed.split('-') year = int(dateArray[0]) month = int(dateArray[1]) day = int(dateArray[2]) return datetime.date(year,month,day) if len(argv) > 1: data = open(argv[1],'r') else: data = open('dates.txt', 'r') while True: line = data.readline() if not line: break entry = line.split('\t') dates.append(dashedToDate(entry[0])) description.append(re.sub("\n","",entry[1])) data.close() # create file to put the TeX/Tikz code texfile = open('picture.tex','w') texfile.writelines("\\begin{tikzpicture}") # Styles used texfile.writelines("[datemarker/.style={circle,draw=black,fill=white,radius=4pt},\n") texfile.writelines("textlabel/.style={anchor=west,text height=1.7ex,text depth=.25ex}]\n") # Draw the background texfile.writelines("\\draw (0,0) -- (0,"+ str(lengthOfLine)+ ");\n") startDate = dates[0] endDate = dates[0] for x in range(len(dates)): if dates[x] < startDate: startDate = dates[x] if dates[x] > endDate: endDate = dates[x] span = (endDate - startDate).days # Draw the dates for x in range(len(dates)): diff = (dates[x] - startDate).days month = monthNames[dates[x].month-1] dateText = month+" "+str(dates[x].day)+", "+str(dates[x].year) yCoordOnLine = lengthOfLine - (diff/span)*lengthOfLine textToPrint = dateText +": "+ description[x] texfile.writelines("\\node at (0, "+ str(yCoordOnLine)+ ") [datemarker] {};\n") texfile.writelines("\\draw (0.1, "+ str(yCoordOnLine)+ ") node [textlabel] {"+textToPrint+"};\n") texfile.writelines("\\end{tikzpicture}") texfile.close() textToPrint = dateText +": "+ description[x] texfile.writelines("\\node at (0, "+ str(yCoordOnLine)+ ") [datemarker] {};\n") texfile.writelines("\\draw (0.1, "+ str(yCoordOnLine)+ ") node [textlabel] {"+textToPrint+"};\n") texfile.writelines("\\end{tikzpicture}") texfile.close() |
What it does is read the file in, do all the calculations, and ouputs the following TikZ code into a file called "picture.tex":
\begin{tikzpicture}[datemarker/.style={circle,draw=black,fill=white,radius=4pt},
textlabel/.style={anchor=west,text height=1.7ex,text depth=.25ex}]
\draw (0,0) — (0,10);
\node at (0, 10.0) [datemarker] {};
\draw (0.1, 10.0) node [textlabel] {Feburary 12, 1809: Charles Darwin};
\node at (0, 7.959890463917526) [datemarker] {};
\draw (0.1, 7.959890463917526) node [textlabel] {December 27, 1822: Louis Pasteur};
\node at (0, 7.412210051546392) [datemarker] {};
\draw (0.1, 7.412210051546392) node [textlabel] {September 17, 1826: Bernhard Riemann};
\node at (0, 0.0) [datemarker] {};
\draw (0.1, 0.0) node [textlabel] {Feburary 7, 1877: Godfrey Harold Hardy};
\node at (0, 4.697164948453608) [datemarker] {};
\draw (0.1, 4.697164948453608) node [textlabel] {March 3, 1845: Georg Cantor};
\end{tikzpicture}
You can then include it into a LaTeX document using the tikz package by using the comamnd "\input{picture.tex}" to get:
