# Systems Engineering Wiki (http://seweb.se.wtb.tue.nl)

## Experimenting

experimenting:throughput_flowtime

# Computing throughput and flow time

An example script to compute the throughput of a system and the flow time of an item is listed here

```#!/usr/bin/env python
#
'''

Input:
Lines containing values:
current-time \t product-number \t entry-time

(product-number starts with 0)

Output:
Lines containing values:
line-number \t throughput \t avg-flow-time

'''

import sys

line_count = 0
avg_flow_time = 0.0

line_count = line_count + 1

values = line.split("\t")
assert len(values) == 3 # We should have 3 values on a line

cur_time = float(values[0])
prod_number = int(values[1])
entry_time = float(values[2])
#print "line= %f %d %f" % (cur_time, prod_number, entry_time)

throughput = float(line_count) / cur_time

avg_flow_time = (line_count - 1) / float(line_count) * avg_flow_time \
+ (cur_time - entry_time) / float(line_count)

print "%d\t%f\t%f" % (line_count, throughput, avg_flow_time)```

Save this script as `calc_tp_aft.py`.

You can use this script with a Chi simulation with a line like

`\$ startmodel mymodel | python calc_tp_aft.py`

or (if you previously captured the output in a file `my_output`):

`\$ cat my_output | python calc_tp_aft.py`

The results of the computation are put on the screen. If you want to capture it in a file, append `“> results.txt”` as in

`\$ startmodel mymodel | python calc_tp_aft.py > results.txt`
experimenting/throughput_flowtime.txt · Last modified: Wednesday, 29 August 2007 : 16:40:23 (external edit)