VSCRIPT FAQ

This is a FAQ for vscript. These are frequently asked questions and is a document that is living. Please feel free to contribute questions and answers to this list.

Note: Anything with >>> at the beginning of the line is to be entered on the vscript prompt.

Note: Anything with ... at the beginning of the line is a command that has not be completed yet.

How can I open a dss file?
Enter on the prompt the following :-

>>> g=opendss('file.dss') # for local access
>>> g=opendss('/xyz/data/file.dss','iep'); # for remote access on iep

How do I display a dss file ?
First open the dss file ( as explained in 1 ). Then
```
>>> GroupFrame(g);
	
```
I want to keep only pathnames which have the word flow in them ?
```
>>> g = opendss('file.dss')
>>> g.filterBy('flow') 
	
```

I want to see all the data in two files...

>>> g1 = opendss('file1.dss')
>>> g2 = opendss('file2.dss')
>>> g3 = g1 + g2
>>> GroupFrame(g3)

I want to find out the number of data sets in a dss file...
```
>>> g = opendss('file.dss')
>>> len(g)
	
```
I want to keep only pathnames in which the b part has 'xyz' in it
```
>>> g = opendss('file.dss')
>>> g.filterBy(1,PathPartPredicate('xyz',Pathname.B_PART))
	
```
1. I want to create a new group that contains only pathnames in which the b part has 'xyz' in it
```
>>> g2 = find(g,'xyz','b')
	    
```
2. I want to create a new group that contains only pathnames in which the bpart DOES NOT have 'xyz'
```
>>> g2 = find(g,'xyz','b',0)
	    
```
I want to reject only pathnames in which the c part starts with 'jk'...
```
>>> g = opendss('file.dss')
>>> g.filterBy(0,PathPartPredicate('^jk',Pathname.C_PART))
	
```
Note: The 0 in the first argument means reject matching
1. Again if we want to create a new group from the existing group that contains only the pathnames having jk as the starting words in the c part we can do
```
>>> g = opendss('file.dss')
>>> g2 = find(g,'^jk','c')
	
```
2. or to reject them do
```
>>> g2 = find(g,'^jk','c',0)
	
```

I want to keep only pathnames in which the b part is exactly 'xyz'

>>> g = opendss('file.dss')
>>> g.filterBy(1,PathPartPredicate('^xyz$',Pathname.B_PART))

again to create a new group with such a filter do

>>> g2 = find(g,'^xyz$', 'b')

I want to keep pathnames that have 'xy' or 'zz' in the b part ...

>>> g = opendss('file.dss')
>>> g.filterBy(1,PathPartPredicate('xy|zz', Pathname.B_PART))

I want to sort a group by the c part in deceasing order

>>> g = opendss('file.dss')
>>> sort(g,"C",0)

or in the increasing order as

>>> sort(g,'C',1)

I want to sort a group by first the b part in increasing order then the c part in decreasing order only if the b part is the same We have a stable sort programmed in vista so its just a matter of doing the sort in the appropriate order
```
>>> g = opendss('file.dss')
>>> sort(g,"B",1)
>>> sort(g,"C",0)
      
```

I want to make a group out of the first 10 pathnames...

>>> g = opendss('file.dss')
>>> refs = Group.createGroup('first 10 paths',g[0:10])

I want the last 10 pathnames

>>> g = opendss('file.dss')
>>> refs = Group.createGroup(last 10 paths',g[-10:])

I want to get the data from a pathname in a dss file Let's say that the pathname has a c part of 'FLOW' and a b part of 'XYZ' then

>>> g = opendss('file.dss')
>>> g.filterBy(1,PathPartPredicate('^FLOW$',Pathname.C_PART))
>>> g.filterBy(1,PathPartPredicate('^XYZ$',Pathname.B_PART))

or in a much easier way to do the same thing but generating a new group containing the filtered pathnames one can do

>>> g2 = find(g,'^FLOW$','c')
>>> g2 = find(g2,'^XYZ$','b')

or in on step as

>>> g2 = find (find(g,'^FLOW$','c'), '^XYZ$', 'b')

How do I display a dss pathname?
First open the dss file
```
>>> g = opendss('file.dss')
      
```
Now get the first reference in this file and plot it
```
>>> ref1 = g[0]
>>> plot(ref1)
      
```
Now get the first reference in this file and tabulate it
```
>>> ref1 = g[0]
>>> tabulate(ref1)
      
```
How do I display more than one dss pathnames together
First open the dss file
```
>>> g = opendss('file.dss')
      
```
Now get the first reference in this file and plot it
```
>>> ref1 = g[0]
>>> ref2 = g[1]
>>> ref3 = g[2]
>>> plot(ref1,ref2,ref3)
      
```
Now get the first reference in this file and tabulate it
```
>>> tabulate(ref1,ref2,ref3)
      
```

I only want pathnames that have a certain time window.

>>> tw = timewindow('01JAN1990 0000 - 01JAN1992 0000')
>>> mylist = []
>>> for ref in g:
...  ref2 = DataReference.create(ref,tw)
...  if ref2: mylist.append(ref2)
... 
>>> g = Group.createGroup('time windowed', mylist)
>>> GroupFrame(g)

I want to export a few data sets to text files...

>>> ref = g[0]
>>> writeascii('junk.txt',ref.getData())

if you want the flags as well

>>> writeascii('junk.txt',ref.getData(),1)

how can i read from a text file a time series and then save it to a dss file

>>> import vutils

for regular time series

>>> vutils.read_dssts('test.dssts')

or for irregular time series

>>> vutils.read_dssits('test.dssits')

I want to plot two time series versus each other. (Scatter plot)

>>> refx = g[0]
>>> refy = g[1]
>>> scatterplot(refx,refy)

I want to write out a few of the data referenes to a filename...

>>> reflist = g[0:5]
>>> for ref in reflist:
...  writedss('xyz.dss', ref.getPathname().toString(), ref.getData())

how do i do a period average/min/max?

>>> ref = g[0]
>>> ref_pa = per_avg(ref)
>>> ds1 = ref.getData()
>>> ds1_pa = vutils.per_avg(ds1_pa)
>>> ds1_pa = vutils.per_max(ds1_pa)
>>> ds1_pa = vutils.per_min(ds1_pa)

how do i do a moving average?

>>> ref = g[0]
>>> ref_ma = vutils.mov_avg(ref)

how do i do a tidal average

>>> ref_tidal_avg = vutils.tidal_avg(ref)

how can i do math operations on a time series

>>> ref1, ref2 = g[0], g[5]
>>> ds1 = ref1.getData()
>>> ds2 = ref2.getData()
>>> ds12_add = ds1+ds2
>>> ds12_div = ds1/ds2
>>> ds1_add = ds1+5.3
>>> dsc = 2*ds1-5.3*ds2+4.5

what else can i do with a time series

>>> ds = ref.getData()
>>> print ds.getTimeWindow()
>>> print ds[0], ds[5]
>>> print ds[0:5]
>>> print ds[-10:]
>>> for e in ds: print e

how can i do a first difference on a time series
```
>>> ds_1stdiff = ds1 - (ds1 << 1) 
```

how can i save a time series generated from math operations

>>> writedss('junk.dss','/MY COMP/DATA/FLOW//15min/mathops/',2*ds1-5.4*ds2)

how can i create my own time series and save/load it later

>>> x = range(50)
>>> y = map(Math.sin,x)
>>> rts = RegularTimeSeries('/MY RTS/MY DATA/MY TYPE//5MIN/MYSOURCE','01jan1977 0100', '5min',y)

how can i retrieve data for a few pathnames from a huge dss file sitting over the network without having to download it all

>>> g=opendss('/export/home/www/htdocs/dss/db/hydro.dss','iep.water.ca.gov')
>>> g2 = find(g,'flow')
>>> for ref in g2:
...  writedss(ref.getFilename(), ref.getPathname().toString(),ref.getData())

how can i set / retrieve flags

Here's an example of setting missing value -901.0 and -902.0 to have missing value flags

>>> ds = ref.getData()
>>> dsi = ds.getIterator()
>>> uId = DSSUtil.getUserId()
>>> while not dsi.atEnd():
...  e = dsi.getElement()
...  if e.y == -901.0 or e.y == -902.0: 
...   FlagUtils.setQualityFlag(e,FlagUtils.REJECT_FLAG,uId)
...   dsi.putElement(e)
...  dsi.advance()

how can i set flags for data outside a certain range
This has already been done in vutils
```
>>> import vutils
>>> vutils.checkRange(ref, 0.0, 5000.0)
      
```
how can i clear flags?

do just as in FAQ 26 and replace the reject flag setting with this line
```
...   FlagUtils.clearAllFlags(e,0)
      
```
how about generating customized plots and in a batch mode
Use VPlotter

how can i do time manipulation

creating a time object
```
>>> tm = time('01jan1990 0100')
	  
```

creating a time with an increment or decrement

>>> tm1 = tm + '1hour'
>>> tm2 = tm - '1day'

difference between 2 times in minutes
```
>>> diff = tm2 - tm1
	  
```
creating a time interval
```
>>> ti = timeinterval('1hour')
	  
```
creating a time from addition/subtraction from a time
```
>>> tm2 = tm + ti
>>> tm3 = tm - ti
	  
```

creating a time interval from another interval

>>> ti = timeinterval('1hour')
>>> ti2 = 2*ti + ti
>>> ti3 = timeinterval('1day')
>>> ti4 = ti3+ti2
>>> ti5 = ti3+ti
>>> print ti5/ti
>>> print (tm-tm2)/ti

how can i learn more about specific objects being used
Look at the conceptual faq.
I can't find the answer to my question...
1. Read the documentation
2. Using the mailing list to post your question to other users
3. talk to me.

VSCRIPT FAQ

Note: Anything with >>> at the beginning of the line is to be entered on the vscript prompt.

Note: Anything with ... at the beginning of the line is a command that has not be completed yet.

Note: The 0 in the first argument means reject matching