Tafkas

[Python] Two loops on list

2011-10-20T03:19:46-07:00

I want to apply some calculation on the elements of list in python. In Java I would have done to for-loops. Is there a more pythonic way to do that?

[1,2,3,4,5] --> 1 with 2, 1 with 3, ..., 4 with 5

def foo(mylist):
    magic  = 0
    for i in range(len(mylist)-1):
        for j in range(i, len(mylist)):
            ### do some magic ###
    return magic

[Ruby] Exception Handling in Ruby

2010-03-19T23:38:19-07:00

I have the following code where I parse a text and try to retrieve some information to store it in a database. Unfortunately sometimes there is no data and I have to set the value to "null". Essentially I have just a couple of these blocks there. My approach just does not seem right.

begin
  data["body"] = content[1].split(/\W{2,}/)[0].strip()
rescue Exception => e
  data["body"] = "null"
end
begin
  data["height"] = content[2].split(/\W{2,}/)[0].strip()
rescue Exception => e
  data["height"] = "null"
end
begin
  data["status"] = content[7].split(/\W{2,}/)[0].strip()
rescue Exception => e
  data["status"] = "null"
end
begin
  data["country"] = content[8].split(/\W{2,}/)[1].strip()
rescue Exception => e
  data["country"] = "null"
end
begin
  data["zip"] = content[9].split(/\W{2,}/)[0].strip()
rescue Exception => e
  data["zip"] = "null"
end
begin
  data["location"] = content[10].split(/\W{2,}/)[0].strip()
rescue Exception => e
  data["location"] = "null"
end

[Python] Return the indexes of specific elements of the list

2010-01-28T19:53:25-08:00

The function takes an list of floats ranging from 0.0 to 100.0 in an ascending order. It returns a list of indexes with the indexes of the elements closest to 25.0, 50.0 and 75.0.

The intention is to label a time axis, where the labels should correspond to their relative position.

def get_pos(rel_dates):
    """returns the positions of the dates closest to 25%, 50%, and 75%"""
    pos = [0] # first element
    dates25, dates50, dates75 = [], [], []
    for date in rel_dates:
        dates25.append(abs(date-25))
        dates50.append(abs(date-50))
        dates75.append(abs(date-75))
    pos.append(dates25.index(min(dates25)))
    pos.append(dates50.index(min(dates50)))
    pos.append(dates75.index(min(dates75)))
    pos.append(len(rel_dates)-1) #last element
    return pos

[Python] Scale data points with the relative distance based on time

2010-01-22T12:55:27-08:00

In order to print a chart that will separate each data point with the relative distance based on time the data has to be scaled.
The parameter "dates" is an array of unix timestamps.

def scale_dates(dates):
    rel_dates = []
    first_day = dates[0]
    last_day = dates[-1]
    d = last_day - first_day
    for date in dates:
        date = float(date-first_day)/(d)
        rel_dates.append(date)
    return rel_dates