Python PSS/E get output as variable

Question

I am power engineer and I often use python in PSS/E program. I am stacked and I want your help as programmers. I have this small code:

import os,sys

PSSE_LOCATION = r"C:\Program Files\PTI\PSSE33\PSSBIN"
sys.path.append(PSSE_LOCATION)
os.environ['PATH'] = os.environ['PATH'] + ';' +  PSSE_LOCATION

import psspy
import redirect
redirect.psse2py()

#--------------------------------
# PSS/E Saved case

CASE = r"""D:\xxx\Desktop\TESTING\SUMMAX.sav"""

if __name__ == '__main__':
    psspy.psseinit(2000)
    psspy.case(CASE)
    psspy.fnsl(
        options1=0, # disable tap stepping adjustment.
        options5=0, # disable switched shunt adjustment.
    )
    psspy.fdns([0,0,0,1,1,0,99,0])
    psspy.area_2(0,1,1)

Code redirect.psse2py() prints the program report in Console. Can you help me to get those outputs as variable?

Answer 1

Given I don't know much about PSSE, you can try the following:

import sys
import io

out, err = io.StringIO(), io.StringIO()
sys.stdout = out
sys.stderr = err

# rest of your code here

# once your code is finished

results = out.getvalue()
errors = err.getvalue()

Answer 2

My favorite solution so far is based on @J.F Sebastian answer Redirect stdout to a file in Python?.

Using the psspy.report_output() and related functions at first seemed like the best option, but they are a little painful because you can only write to a file and not a StringIO buffer.

Here is a complete example:

import contextlib
import sys

# Auto-magically setup PSSE environment.  
# You can do this step the hard way if you want
import pssepath
pssepath.add_pssepath()

import psspy
import redirect
redirect.psse2py()
psspy.psseinit(50000)

@contextlib.contextmanager
def redirect_stdout(new_target):
    old_target, sys.stdout = sys.stdout, new_target # replace sys.stdout
    try:
        yield new_target # run some code with the replaced stdout
    finally:
        sys.stdout = old_target # restore to the previous value


import StringIO
f = StringIO.StringIO()
print "before redirect"
with redirect_stdout(f):
    psspy.report('123xxx(report)')
    psspy.alert('abcyyy(alert)')
    psspy.progress('foobar(progress)')
    f.seek(0)
    var = f.read()

print "after redirect"
print "var: %s" % var

which prints:

< snip PSSE init copyright header>
before redirect
after redirect
var: 123xxx(report)
abcyyy(alert)
foobar(progress)