Help with calcuations using imported numbers.

[mott3510]

I have imported two columns of numbers from excel and now i need to use those two columns of numbers to calculate the following...

Average_Error = sum(map(lambda a, b: abs(a - b), My_High, Actual_High))/delta.days

I need the first column to be inserted where I have My_High in the code above, and I need the second column to be inserted where I have Actual_High in the code above. I used the following code to import the numbers...

f = open("C:\users\cory\desktop\Verification.csv")
dd = {}
keys = f.readline().strip().split(',')
for key in keys:
    dd.setdefault(key, [])
 
for line in f:
    for i, item in enumerate(line.strip().split(',')):
        dd[keys[i]].append(int(item))
 
f.close()

I don't know where to begin.

Thanks!

[bvdet]

Please use code tags when posting code. See this link.

What is delta.days?

Access the list My_High like this:

dd['My_High']

[mott3510]

delta.days is just the number of days in between two dates...

 

today = datetime.date.today()
date_format = "%m/%d/%Y"
d0 = date(2009, 6, 21)
d1 = today
delta = d1-d0
print delta.days

I have this as my code now...

f = open("C:\users\cory\desktop\Verification.csv")
dd = ['My_Highs']
keys = f.readline().strip().split(',')
for key in keys:
    dd.setdefault(key, ['My_Highs'])
 
for line in f:
    for i, item in enumerate(line.strip().split(',')):
        dd[keys[i]].append(int(item))
 
f.close()

...and I am getting this error message...Attri bute Error: 'list' object has no attribute 'setdefault'

[bvdet]

Evidently you did not look at the code to understand what is happening. I will attempt to explain with embedded comments:

# Create an open file object for reading.
f = open('your_file.csv')
# Initialize an empty dictionary.
dd = {}
# Read the first line in the file.
# These are the column labels.
# We will use these labels as the dictionary keys.
# Create a list by splitting the string on the comma.
keys = f.readline().strip().split(',')
# Iterate on the list of labels.
for key in keys:
    # Using dictionary method setdefault, assign each dictionary
    # key to an empty list.
    dd.setdefault(key, [])

# Iterate on the file object.
# This iteration begins with line 2 because we already read the first line.
for line in f:
    # Create a list of scores out of each line by splitting the string
    # on the comma character. Iterate on the list of scores.
    for i, item in enumerate(line.strip().split(',')):
        # Append each score to the value of the corresponding 
        # dictionary key. Type cast the score to int.
        dd[keys[i]].append(int(item))

# Close the file object.
f.close()

# Iterate on the list of keys (labels).
for key in keys:
    # Print the key and corresponding dictionary value.
    print "%s: %s" % (key, dd[key])

Study the comments above and post your question again.

[mott3510]

The comments helped a lot, I figured it out! Thanks for all your help.

[bvdet]

You are welcome. I think you learned something.

-BV

[mott3510]

I did! This is only my third day working with python, and I have never written code before so I will more than likely have some more questions with due time.