I've just started playing around with python lists, I've written the simple code below expecting the printed file to display the numbers [12,14,16,18,20,22] but only 22 is displayed. Any help would be great.
a=10
b=14
while a <= 20:
a=a+2
b=b-1
datapoints=[]
datapoints.insert(0,a)
print datapoints
a=10
b=14
datapoints=[] # this needs to be established outside of your loop
while a <= 20:
a=a+2
b=b-1
datapoints.append(a)
print datapoints
You need to set up datapoints outside your loop, and then inside your loop, append each additional datum to datapoints
Joel already answered but if you want a more compact code you can use range
numbers = []
for number in range(12,24,2):
# do whatever you want with b
numbers.append(number)
print numbers
or if you only want to print the numbers you can do
print [number for number in range(12,24,2)]
you can achieve the expected list as output by using the range() method. It takes three parameters, start, stop and step.
data_points = range(12, 23, 2) # range returns list in python 2
print data_points
Note that, in python 3 the range() is a sequence-type. So, you will have to cast it to list in python 3
data_points = list(range(12, 23, 2)) # python 3
print(data_points)
datapointsto an empty list in the loop. I suggest you move thedatapoints=[]line to take place outside of the loop.list.append()if you expected numbers to be added at the end, which your expected output suggests you want.bhave a purpose?collections.dequeso you can callappendleftand perform the prepend efficiently (lists only have efficient appends on the right, prepending isO(n)).whileis often not that pythonic IMO for a case like this, consider using aforloop instead in combination withrange