[Zope] Script writing to session: bizarre result or just a mistake?

[Redding, Matthew]

Hi All,

I was wondering if anyone could tell me why this python script (passed
no parameters)
creates session values for N_prod, N_shed, N_screen, N_pond, N_land,
N_soil that 
are all the same (and TS_*, K_*, P_* values that are similarly the same
within their set).

What am I doing wrong?  Is this a vaguery of the script system, and
should I use 
an external method instead?


#This function uses the session data, and a range of coded
#values to determine the quantities of TS, N, P, and K
#remaining at each step of the process up to land application.
#On Entry:  requires the Session data values gest, lact, suckers,
#weaners, growers, finish, gilt, and boars.
#On Exit: returns the modified session data, with additional values
#representing the manure produced, Efluent exiting the shed, Effluent
#after the screens (if there are any), pond sludge component, pond
liquid,
#quantities reaching the soil during irrigation, quantity remaining in
the
soil
#following losses: each of these for each of TS, N, P, and K.
import math
session=context.REQUEST.SESSION

#Define loss values:
ts_shed=0; ts_screen=20
N_shed=10;N_screen=8;N_sludge=24;N_pond=40;N_irrigation=25;N_soil=25
P_shed=0;P_screen=11;P_sludge=90;P_pond=0;P_irrigation=0;P_soil=0
K_shed=0;K_screen=0;K_sludge=10;K_pond=0;K_irrigation=0;K_soil=0

#Calculate Components at each step, and assign to the session.
#_Manure Production
session['TS_prod']=session['num_spu']*109.95
#session['N_prod']=round(session['num_spu']*0.081814, 1)
session['N_prod']=session['num_spu']*0.081814
#session['P_prod']=round(session['num_spu']*0.33338, 1)
session['P_prod']=session['num_spu']*0.33338
#session['K_prod']=round(session['num_spu']*0.8335, 1)
session['K_prod']=session['num_spu']*0.8335

#_exiting the shed
session['TS_shed']=round(session['TS_prod']*(1-(ts_shed/100)),1)
session['N_shed']=round(session['N_prod']*(1-(N_shed/100)),1)
session['P_shed']=round(session['P_prod']*(1-(P_shed/100)), 1)
session['K_shed']=round(session['K_prod']*(1-(K_shed/100)), 1)

#_exiting the screens
session['TS_screen']=round(session['TS_shed']*(1-(ts_screen/100)), 1)
session['N_screen']=round(session['N_shed']*(1-(N_screen/100)), 1)
session['P_screen']=round(session['P_shed']*(1-(P_screen/100)), 1)
session['K_screen']=round(session['K_shed']*(1-(K_screen/100)), 1)

#_retained in sludge
session['N_sludge']=round(session['N_screen']*(N_sludge/100), 1)
session['P_sludge']=round(session['P_screen']*(P_sludge/100), 1)
session['K_sludge']=round(session['K_screen']*(K_sludge/100), 1)

#_retained in the ponds
session['N_pond']=round((session['N_screen']-session['N_sludge'])*(1-(N_
pond/
100)), 1)
session['P_pond']=round((session['N_screen']-session['N_sludge'])*(1-(P_
pond/
100)), 1)
session['K_pond']=round((session['N_screen']-session['N_sludge'])*(1-(K_
pond/
100)), 1)

#_reaching the soil
session['N_lands']=round(session['N_pond']*(1-(N_irrigation/100)), 1)
session['P_lands']=round(session['P_pond']*(1-(P_irrigation/100)), 1)
session['K_lands']=round(session['K_pond']*(1-(K_irrigation/100)), 1)

#_retained in the soil
#session['N_soil']=round(session['N_lands']*(1-(N_soil/100)), 1)
session['N_soil']=session['N_lands']*(1-(N_soil/100))
#session['P_soil']=round(session['P_lands']*(1-(P_soil/100)), 1)
session['P_soil']=session['P_lands']*(1-(P_soil/100))
#session['K_soil']=round(session['K_lands']*(1-(K_soil/100)), 1)
session['K_soil']=session['K_lands']*(1-(K_soil/100))

return

-------------------------------------------------------
THanks, 

Matt Redding

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