hi everyone,

I am having issues with an assignment for university. I know that you are not here to do my work for me but I could really use a little help.

My assignment involves a parse file that the uni tutors have written for us and we have to add to it to create a program that creates graphs of the data in the file that the parse file program reads.

I am stuck on one of them, what I want to do is access the voltages in the parse file (it has put the data into 3 arrays, one is a time, another a voltage and the third the numData) and if the voltage is over a certain point create another array that records the voltage as 1 and if its under records it as a 0. that way I can show when for each time step the voltage is over a certain point.

I have been trying to write this for 2 days.... I just cant figure it out.
Please help!

Okay, so post your code and tell us what the errors that you're getting are. What are you stuck on?

ok this is the code they wrote for us:

from __future__ import division
from pylab import *
from numpy import *

# This function reads in a file containing space-separated pairs of
# values (one pair of values per line) and parses it.
#
# To use this function, have the file with the data in the same folder
# as this program. Use this function as follows:
#
# (xs, ys, n) = parseFile()
#
# The function will then create an input prompt in the Python command window:
#
# >>> Please enter the filename containing the data:
#
# Then type the name of the data file.
# The function will then read the data in that file (note that if the
# filename given is invalid, the function will print an error message
# and ask for the file name again).
#
# This function will return the first column of numbers as xs, the second
# column as ys and the number of values in each array as n.
def parseFile() :

while True :
filename = raw_input("Please enter the filename containing the data: ")

try :
f = open(filename, 'r')
except IOError :
print "Invalid filename"
continue

break

# Create empty lists to store the parsed data
xs = []
ys = []

# For each separate line (splitlines takes into account all
# possible file endings).
for rec in f.read().splitlines() :

# Attempt to read another two space-separated values, silently
# ignore otherwise.
try :
(x,y) = rec.strip().split()
except ValueError :
continue

# Try to convert the two values to floating-point numbers,
# silently ignore otherwise.
try :
x = float(x)
y = float(y)
except ValueError :
continue

# Append the two values to the appropriate lists.
xs.append(x)
ys.append(y)

# Finished reading the file
f.close()

# Convert the lists to arrays
xs = array(xs)
ys = array(ys)

print size(xs), "datapoints read from", filename

# Return the array of x values, the array of y values and the number of values.
return (xs, ys, size(xs))


and this is what i have written so far:

# Setting up our initial parameters.

# Read in the data to analyse
(times, voltages, numData) = parseFile()

# Enter threshold
threshold = input('Enter threshold voltage: ')

# Enter bin size
bin_size = input('Enter bin size for times ')

# plot graph D1

plot(times, voltages)
title('Data')
xlabel('Times (ns)')
ylabel('Voltage')
show()

this is the part I am struggling to get to work. I want to use the voltages array and if its above the threshold voltage entered then I want it to have a value of 1 and if its below the threshold I want it to have a value of 0. that way when i plot the times v the 1 or 0 I can see spikes where it has gone over the threshold voltage>

# plot D2

A = array(voltages)
B = A => threshold
print B

(this is just giving me a list of true or false for each value)

Please use code tags when posting code in this forum like so:
[code=python] # Code goes inside these tags

[/code]

As far as your "plot D2" code, that should be giving you a syntax error, since => is not valid in Python. What exactly is that line supposed to do? As I read it: B = A => threshold means you want to evaluate A >= threshold (if the value of A is greater than or equal to the value of threshold ) and then store it in B , which would naturally return either True or False.

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