How can I programmatically generate PDFs using LaTeX? - django

I'm trying to generate some LaTeX code which from thereon should generate PDF documents.
Currently, I'm using the Django templating system for dynamically creating the code, but I have no idea on as how to move on from here. I understand that I could save the code in a .tex file, and use subprocess to run pdflatex for generating the PDF. But I had so much trouble escaping the LaTeX code in "plain" Python that I decided to use the Django templating system. Is there a way that I could somehow maybe pipe the output produced by Django to pdflatex? The code produced is working properly, it's just that I do not know what to do with it.
Thanks in advance

I was tackling the same issue in a project I had previously worked on, and instead of piping the output, I created temporary files in a temporary folder, since I was worried about handling the intermediate files LaTeX produces. This is the code I used (note that it's a few years old, from when I was still new to Python/Django; I'm sure I could come up with something better if I was writing this today, but this definitely worked for me):
import os
from subprocess import call
from tempfile import mkdtemp, mkstemp
from django.template.loader import render_to_string
# In a temporary folder, make a temporary file
tmp_folder = mkdtemp()
os.chdir(tmp_folder)
texfile, texfilename = mkstemp(dir=tmp_folder)
# Pass the TeX template through Django templating engine and into the temp file
os.write(texfile, render_to_string('tex/base.tex', {'var': 'whatever'}))
os.close(texfile)
# Compile the TeX file with PDFLaTeX
call(['pdflatex', texfilename])
# Move resulting PDF to a more permanent location
os.rename(texfilename + '.pdf', dest_folder)
# Remove intermediate files
os.remove(texfilename)
os.remove(texfilename + '.aux')
os.remove(texfilename + '.log')
os.rmdir(tmp_folder)
return os.path.join(dest_folder, texfilename + '.pdf')
The dest_folder variable is usually set to somewhere in the media directory, so that the PDF can then be served statically. The value returned is the path to the file on disk. The logic of what its URL would be is handled by whatever function sets the dest_folder.

Related

How do I change the sympy preview directory?

When I execute
sp.preview(expression, viewer = “file”, filename = “expression.png”)
SymPy automatically saves the preview in C:\Users\my username.
How do I change the save path?
I'm not sure if there is a canonical way to do this, but you can get the SYMPY_PATH as
from sympy.testing.tests.test_code_quality import SYMPY_PATH
and at least add that as a prefix to your filename (however your system likes paths added). If that works and puts it in the SymPy directory then you can use any path where you would like the file to go.

Problem reading file with pandas uploaded to a django view

I'm uploading some excel and csv files to a django view using axios, then i pass those files to a function that uses pandas read_csv and read_excel functions to process them, the first problem i had was with some excel files that had some non utf-8 characters that pandas was unable to read, the only solution i found was to set "engine = 'python'" when reading the file (changing the encoding to utf-8-sig or utf-16 didn't work).
This works when i'm testing the script from my terminal, but when i use the same script on a view i get the following error: ValueError("The 'python' engine cannot iterate through this file buffer.")
This is the code i'm using:
try:
data = pandas.read_csv(request.FILES['file'], engine="python")
except:
print("Oops!",sys.exc_info(),"occured.")
trying the same function through the terminal works fine
pandas.read_csv("file.csv", engine="python")

How to install LaTeX class on Heroku?

I have a Django app hosted on Heroku. In it, I am using a view written in LaTeX to generate a pdf on-the-fly, and have installed the Heroku LaTeX buildpack to get this to work. My LaTeX view is below.
def pdf(request):
context = {}
template = get_template('cv/cv.tex')
rendered_tpl = template.render(context).encode('utf-8')
with tempfile.TemporaryDirectory() as tempdir:
process = Popen(
['pdflatex', '-output-directory', tempdir],
stdin=PIPE,
stdout=PIPE,
)
out, err = process.communicate(rendered_tpl)
with open(os.path.join(tempdir, 'texput.pdf'), 'rb') as f:
pdf = f.read()
r = HttpResponse(content_type='application/pdf')
r.write(pdf)
return r
This works fine when I use one of the existing document classes in cv.tex (eg. \documentclass{article}), but I would like to use a custom one, called res. Ordinarily I believe there are two options for using a custom class.
Place the class file (res.cls, in this case) in the same folder as the .tex file. For me, that would be in the templates folder of my app. I have tried this, but pdflatex cannot find the class file. (Presumably because it is not running in the templates folder, but in a temporary directory? Would there be a way to copy the class file to the temporary directory?)
Place the class file inside another folder with the structure localtexmf/tex/latex/res.cls, and make pdflatex aware of it using the method outlined in the answer to this question. I've tried running the CLI instructions on Heroku using heroku run bash, but it does not recognise initexmf, and I'm not entirely sure how to specify a relevant directory.
How can I tell pdflatex where to find to find the class file?
Just 2 ideas, I don't know if it'll solve your problems.
First, try to put your localtexmf folder in ~/texmf which is the default local folder in Linux systems (I don't know much about Heroku but it's mostly Linux systems, right?).
Second, instead of using initexmf, I usually use texhash, it may be available on your system?
I ended up finding another workaround to achieve my goal, but the most straightforward solution I found would be to change TEXMFHOME at runtime, for example...
TEXMFHOME=/d pdflatex <filename>.tex
...if you had /d/tex/latex/res/res.cls.
Credit goes to cfr on tex.stackexchange.com for the suggestion.

Temporary file with specific file extension in Python 3

I am writing some unit tests for a piece of code that takes a path and attempts to load the file if it has a known extension, then does more careful checking.
In the unit test, I would like to create a temporary file that has the correct extension, but incorrect contents, in my case an empty file posing as test.tif.
How can I create a temporary file while specifying the extension (or the entire name), using the tempfile module?
I have looked at the NamedTemporaryFile class, as well as the suffix and prefix parameters, but I still cannot set the extension. I suppose I could manually create a file in a temporary directory, but then I loose the self-deleting capability that I am after.
This doesn't work for you?
In [2]: tempfile.NamedTemporaryFile(suffix='.tif').name
Out[2]: '/var/folders/gq/swc6jtld5853skyq_xc2lpc40000gn/T/tmplrtwvxg7.tif'
did you try?
fd, path =tempfile.mkstemp(suffix = '.tif')
print(path)

Can't save figure as .eps [gswin32c is not recognized]

I'm using Enthought Canopy with PyLab(64-bit). For my report I need to use Latex (XeLaTex) and the plots are done with matplotlib.
To have an first idea I just copied the second example from http://matplotlib.org/users/usetex.html and compiled it. It looks fine and I can save it as a normal png without problems. However if i try to save it as .eps or.ps it does not work and an error appears:
invalid literal for int() with base 10: "
Additionaly in the Pylab shell it shows:
'gswin32c' is not recognized as an internal or external command, operable program or batch file'.
If I save it as .pdf I have no problems except the text is all black instead of being red and blue. This is a problem because in my plots I have two axes and I need them colorized for better readability.
If I then try to delete some lines from the example given (all text) I still cannot save it as .eps nor .ps. I can't figure out the problem and all the other topics related to this have not given me an insight. So I really need your help because I can't use .png for my report.
Thank you in advance!!!
I finally managed to solve this problem. It might look weird but maybe other people can benefit from it.
The solution might depend upon the software you use. I use Enthought Canopy (Python) and MikTeX 2.9 under W8 64bit.
If you want to output .ps and .eps files with matplotlib using the 'text.usetex': True option then you will encounter the problem posted above.
Solution:
Download and install Ghostscript (32bit) from http://www.ghostscript.com/download/gsdnld.html.
Download ps2eps-1.68.zip from http://www.tm.uka.de/~bless/ps2eps. The proceeding is given in the manual, however I like to point out the part with the environment variables. In this last step you need to go to Control Panel --> System --> Advanced system settings. Then click on the header 'Advanced' and on the bottom of the window you see 'Environment Variables' on which you click. Then you use the 'New'-Button for User Variables for USERNAME. Then you type in as variable name 'ps2eps' and for variable value you type in the actual path where you have saved the ps2eps.pl file. In my case this is 'C:\Program Files (x86)\ps2eps\bin\'. You can check if you type 'ps2eps' in the command-window.
Download xpdfbin-win-3.03.zip from http://www.foolabs.com/xpdf/download.html. You only need the file 'pdftops.exe'. However I could not assign a path like in step 2. I solved this by putting the 'pdftops.exe' in the MikTeX 2.9 folder. The exact location for me was 'C:\Program Files\MiKTeX 2.9\miktex\bin\x64'.
I was then able to save figures as .ps and have no more any error messages. Remember to use the settings proposed on http://matplotlib.org/users/usetex.html under 'postscript options'.
In myself used the following settings:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import matplotlib as mpl
mpl.rc('font', **{'family':'serif', 'serif':['Computer Modern Roman'],
'monospace':['Computer Modern Typewriter']})
params = {'backend': 'ps',
'text.latex.preamble': [r"\usepackage{upgreek}",
r"\usepackage{siunitx}",
r"\usepackage{amsmath}",
r"\usepackage{amstext}",],
'axes.labelsize': 18,
#'axes.linewidth': 1,
#'text.fontsize':17,
'legend.fontsize': 10,
'xtick.labelsize': 13,
#'xtick.major.width' : 0.75,
'ytick.labelsize': 13,
'figure.figsize': [8.8,6.8],
#'figure.dpi': 120,
'text.usetex': True,
'axes.unicode_minus': True,
'ps.usedistiller' : 'xpdf'}
mpl.rcParams.update(params)
mpl.rcParams.update({'figure.autolayout':True})
(whereas many of the params are just for my own purpose later in the plots)
As a beginner I am not well informed about the dependence from the 'backend' used if you are running a script from your python console. I however used this without any --pylab settings in before and I do not know if one needs to switch the backend manually if he is working already in a console with a specific matplotlib backend.
I had the same problem and my problem was a font adjustment in the python code that is :
from matplotlib import rc
rc('font',**{'family':'sans-serif','sans-serif':['Helvetica']})
rc('text', usetex=True)
when I remove this iit works fine and now i can save eps.
So be sure that any shortest working example is working for you or not then check the font and other style edits in your code. This may help.