I am building many models using pyomo, and from what I understand, pyomo reformulates models before solving them.
I want to know exactly what the model looks like when it gets passed to the solver files ipopt and couenne.
From what I see here it is not clear to me how to get the nl file from a script (but I see how to get it from the command line).
Here is how I am solving the models in pyomo:
ipopt_solver = SolverFactory('ipopt')
ipopt_results_solver = ipopt_solver.solve(my_model, tee=True)
print ipopt_results_solver
couenne_solver = SolverFactory('couenne')
couenne_results_solver = couenne_solver.solve(my_model, tee=True)
print couenne_results_solver
How do I get the nl file just before solving? (and I assume it is just as easy to spit out another format other than nl).
If you just want the NL file, you can call the write method on the model with a filename that ends with .nl (e.g., my_model.write('junk.nl').
If you want to tell the solver object to not delete the temporary solver files so that you can access them after the solve, you should add keepfiles=True to the solve call. This will print the location of the temporary solver files. If you need to access them from the script, I believe the NL filename can be found as one of the entries in the _problem_files list attribute on the solver object. The log filename is stored on the _log_file attribute.
Related
I'm new to q and I'm trying to save a file on my Mac. Currently using Jupyter Notebook if that makes a difference.
A quick table:
t:([] c1:`a`b`c; c2:1.1 2.2 3.3)
I first extract my current location by using \cd and i get: "/Users/Gorlomi/Documents/q"
but when I try
`:/Users/Gorlomi/Documents/q set t
I get:
evaluation error:
type
[1] (.q.set)
[0] `:/Users/Gorlomi/Documents/q set t
^
I'm following examples from "Q for Mortals" from the kx website:
https://code.kx.com/q4m3/1_Q_Shock_and_Awe/#11-starting-q
For easy find use cmd (or ctrl) + F and find "t set t"
Thank you in advance.
There are two answers to this question, depending on whether you want to save your file as a flat table, or a splayed table.
If you want to save you table as a flat table, you need to give a file name for your table. Currently, you're just giving it the directory that you want to save it in. So for instance, the following should work for you:
`:/Users/Gorlomi/Documents/q/t set t
If instead, you want to save your table as a splayed table, then you will need to pass it a directory (ideally, one that is not already being used by the file system). To do this, you will pass set a file path with a trailing forward slash. So the following should work for you:
`:/Users/Gorlomi/Documents/q/t/ set t
I have a Python code which is logging some data into a .csv file.
logging_file = 'test.csv'
dt = datetime.datetime.now()
f = open(logging_file, 'a')
f.write('\n "{:%H:%M:%S}",{},{}'.format(dt,x,y,))
The above code is the core part and this produces continuous data in .csv file as
"00:34:09" ,23.05,23.05
"00:36:09" ,24.05,24.05
"00:38:09" ,26.05,26.05
... etc.,
Now I wish to add the following lines in first row of this data. time, data1,data2.I expect output as
time, data1, data2
"00:34:09" ,23.05,23.05
"00:36:09" ,24.05,24.05
"00:38:09" ,26.05,26.05
... etc.,
I tried many ways. Those ways not produced me the result as preferred format.But I am unable to get my expected result.
Please help me to solve the problem.
I would recommend writing a class specifically for creating and managing logs.Have it initialize a file, on creation, with the expected first line (don't forget a \n character!), and keep track of any necessary information about that log(the name of the log it created, where it is, etc). You can then have the class 'write' to the log (append the log, really), you can create new logs as necessary, and, you can have it check for existing logs, and make decisions about either updating what is existing, or scrapping it and starting over.
I have a .mat workspace file containing 4 character variables. These variables contain paths to various folders I need to be able to cd to and from relatively quickly. Usually, when using only Matlab I can load this workspace as follows (provided the .mat file is in the current directory).
load paths.mat
Currently I am experimenting with the Matlab Engine API for Python. The Matlab help docs recommend using the following Python formula to send variables to the current workspace in the desktop app:
import matlab.engine
eng = matlab.engine.start_matlab()
x = 4.0
eng.workspace['y'] = x
a = eng.eval('sqrt(y)')
print(a)
Which works well. However the whole point of the .mat file is that it can quickly load entire sets of variables the user is comfortable with. So the above is not efficient when trying to load the workspace.
I have also tried two different variations in Python:
eng.load("paths.mat")
eng.eval("load paths.mat")
The first variation successfully loads a dict variable in Python containing all four keys and values but this does not propagate to the workspace in Matlab. The second variation throws an error:
File "", line unknown SyntaxError: Error: Unexpected MATLAB
expression.
How do I load up a workspace through the engine without having to manually do it in Matlab? This is an important part of my workflow....
You didn't specify the number of output arguments from the MATLAB engine, which is a possible reason for the error.
I would expect the error from eng.load("paths.mat") to read something like
TypeError: unsupported data type returned from MATLAB
The difference in error messages may arise from different versions of MATLAB, engine API...
In any case, try specifying the number of output arguments like so,
eng.load("paths.mat", nargout=0)
This was giving me fits for a while. A few things to try. I was able to get this working on Matlab 2019a with Python 3.7. I had the most trouble trying to create a string and using the string as an argument for load and eval/evalin, so there might be some trickiness with the single or double quotes, or needing to have an additional set of quotes in the string.
Make sure the MAT file is on the Matlab Path. You can use addpath and rmpath really easily with pathlib objects:
from pathlib import Path
mat_file = Path('local/path/from/cwd/example.mat').resolve # get absolute path
eng.addpath(str(mat_file.parent))
# Execute other commands
eng.rmpath(str(mat_file.parent))
Per dML's answer, make sure to specify the nargout=0 when there are no outputs from the function, and always when calling a script. If there are 1 or more outputs you don't have to have an output in Python, and there is more than one it will be output as a tuple.
You can also turn your script into a function (just won't have access to base workspace without using evalin/assignin):
function load_example_matfile()
evalin('base','load example.mat')
end
eng.feval('load_example_matfile')
And, it does seem to work on the plain vanilla eval and load as well, but if you leave off the nargout=0 it either errors out or gives you the output of the file in python directly.
Both of these work.
eng.eval('load example.mat', nargout=0)
eng.load('example.mat', nargout=0)
I'm extracting extensions from a multi-extension FITS file, manipulate the data, and save the data (with the extension's header information) to a new FITS file.
To my knowledge pyfits.writeto() does the task. However, when I give it a data parameter in the form of an array, it gives me the error:
'AttributeError: 'numpy.ndarray' object has no attribute 'lower''
Here is a sample of my code:
'file = 'hst_11166_54_wfc3_ir_f110w_drz.fits'
hdulist = pyfits.open(dir + file)'
sci = hdulist[1].data # science image data
exp = hdulist[5].data # exposure time data
sci = sci*exp # converts electrons/second to electrons
file = 'test_counts.fits'
hdulist.writeto(file,sci,clobber=True)
hdulist.close()
I appreciate any help with this. Thanks in advance.
You're confusing the HDUList.writeto method, and the writeto function.
What you're calling is a method on the HDUList object that is returned when you call pyfits.open. You can think of this object as something like a file handle to your original drizzled FITS file. You can manipulate this object in place and either write it out to a new file or save updates in place (if you open the file in mode='update').
The writeto function on the other hand is not tied to any existing file. It's just a high-level function for writing an array out to a file. In your example you could write your array of electron counts out like:
pyfits.writeto(filename, data)
This will create a single-HDU FITS file with the array data in the PRIMARY HDU.
Do be aware of the admonishment at the top of this section of the docs: http://docs.astropy.org/en/v1.0.3/io/fits/index.html#convenience-functions
The functions like pyfits.writeto are there for convenience in interactive work, but are not recommendable for use in code that will be run repeatedly, as in a script. Instead have a look at these instructions to start.
It is probably because you should use hdulist.writeto(file, clobber=True). There is only one required argument:
https://pythonhosted.org/pyfits/api_docs/api_hdulists.html#pyfits.HDUList.writeto
If you give a second argument, it is used for output_verify which should be a string, not a numpy array. This probably explains your AttributeError ....
Django and Python newbie here. Ok, so I want to make a webpage where the user can enter a number between 1 and 10. Then, I want to display an image corresponding to that number. Each number is associated with an image filename, and these 10 pairs are stored in a list in a .txt file.
One way to retrieve the appropriate filename is to create a NumToImage model, which has an integer field and a string field, and store all 10 NumToImage objects in the SQL database. I could then retrieve the filename for any query number. However, this does not seem like such a great solution for storing a simple .txt file which I know is not going to change.
So, what is the way to do this in Python, without using a database? I am used to C++, where I would create an array of strings, one for each of the numbers, and load these from the .txt file when the application starts. This vector would then lie within a static object such that I can access it from anywhere in my application.
How can a similar thing be done in Python? I don't know how to instantiate a Python object and then enable it to be accessible from other Python scripts. The only way I can think of doing this is to pass the object instance as an argument for every single function that I call, which is just silly.
What's the standard solution to this?
Thank you.
The Python way is quite similar: you run code at the module level, and create objects in the module namespace that can be imported by other modules.
In your case it might look something like this:
myimage.py
imagemap = {}
# Now read the (image_num, image_path) pairs from the
# file one line at a time and do:
# imagemap[image_num] = image_path
views.py
from myimage import imagemap
def my_view(image_num)
image_path = imagemap[image_num]
# do something with image_path