I have given the following three variables:
start = 30 #starting value
end = 60 #ending value
slice_size = 6 #value difference per tuble
start and end are row numbers of an array. My goal is to create an array/list of tuples, where each tuples includes as much items as slice_size defines. A little example: If start and end have the above values the first four tuples would be:
[[30,35],[36,41],[42,47],[48,53],...].
But now comes the clue: the first value of the next tuple does not start with the first value before + slice_size, but rather with first value + slice_size/2. So I want something like this:
[[30,35],[33,38],[36,41],[39,44],...].
This list of tuples goes on until end is reached or right before it is reached - so until <=end . The last value of the list is not allowed to pass the value of end. The value of slice_size must of course always be an even number to work properly.
My nooby attempt is done by a while loop:
condition = 0
i = 0
list = []
half_slice = int(slice_size /2)
while condition <= end:
list.append([start+int(slice_size/2)*i,start+((slice_size-1)+i*half_slice)])
condition = start+((slice_size-1)+i*int(slice_size/2))
i += 1
The thing is, it works. However I know this is complete rubbish and I want to improve my skill. Do you have a suggestion how to do it in a couple of code lines?
you must not use list as it is a reserved word
import numpy as np
start = 30 #starting value
end = 60 #ending value
slice_size = 6 #value difference per tuble
l = [[i,j] for i,j in zip(np.arange(start, end, slice_size/2),
np.arange(start + slice_size - 1,
end + slice_size - 1,
slice_size/2)
)
]
print(l)
Output:
[[30.0, 35.0],
[33.0, 38.0],
[36.0, 41.0],
[39.0, 44.0],
[42.0, 47.0],
[45.0, 50.0],
[48.0, 53.0],
[51.0, 56.0],
[54.0, 59.0],
[57.0, 62.0]]
1) Do NOT use list as a variable name. It is a reserved key-word.
2) Not a NumPy solution but you can use list comprehension:
start = 30 #starting value
end = 60 #ending value
slice_size = 6 #value difference per tuble
result = [[current, current + slice_size - 1] for current in range(start, end - slice_size + 2, slice_size // 2)]
print(result)
Output:
[[30, 35], [33, 38], [36, 41], [39, 44], [42, 47], [45, 50], [48, 53], [51, 56], [54, 59]]
This will work for an odd number slice_size as well.
Related
I have to make a game where like the lottery my program generates 5 random numbers from a list of numbers 1-50 and one additional number from a list of numbers 1-20 and combines them into a final list that reads eg: (20, 26, 49, 01, 11, + 06) where two numbers are never repeated like (22, 11, 34, 44, 01, + 22) <--- this is what I don't want
attached below is the code I have written yet how do I make it so two numbers or more are never repeated and to add the + into my list without the "" signs
input:
import random
a = list(range(1,51))
b = random.randint(1, 20)
temp = []
for i in range(5):
random.shuffle(a)
temp.append(random.choice(a[:5]))
temp.append('+')
temp.append(b)
print(temp)
output:
[14, 12, 3, 16, 23, '+', 9]
You can not add + without the ' around them - they mark the + as string.
Also: you shuffle your list - simply take the first 5 values - they are random and your list does not contain any dupes so you are golden:
nums = list(range(1,51))
random.shuffle(nums)
five_nums = nums[:5]
print(five_nums) # [44, 23, 34, 38, 3]
To simplyfy it, use:
import random
# creates 5 unique elements from 1..50 and adds a + and a [0-19]+1 number
randlist = random.sample(range(1,51),k=5) + ["+", random.choice(range(20))+1]
print(randlist)
Now you got mixed numbers and strings - you can create a combined string by:
print("You drew {} {} {} {} {} {} {}".format(*randlist))
To create a string like
[48, 2, 9, 6, 41, '+', 8]
You drew 48 2 9 6 41 + 8
Doku:
random.sample (draw without putting back)
You can try the following:
import random
randList, run = [], 0
while run < 6:
number = random.randint(1,51)
if number not in randList:
if run == 5:
randList.append('+'+str(number))
break
randList.append(number)
run += 1
print(randList)
You can't have a string in a list without quotes, however, if you were to print every item in the list (using a for loop or join), the quotes wouldn't be there.
This code will generate a list of 7 random numbers
import random
def main():
numbers = []
for num in range(7):
num = random.randrange(50)
numbers.append(num)
print(numbers)
main()
#No repeating numbers and sorted output
import random
picks = int (input("How Many Picks ?: "))
for i in range (picks):
num_list = random.sample(range(1, 45), 5,)
num_list.sort()
joker_num = random.sample(range(1, 20), 1)
print("Lucky Numbers :", num_list, "-", "Joker :", joker_num)
It didn't work because you need to have
import random
i‘ m using Python 3.7.
I have an Array like this:
L1 = [1,2,3,-10,8,12,300,17]
Now i want to filter the values(the -10 and the 300 is not okay)
The values in the array may be different but always counting up or counting down.
Has Python 3 a integrated function for that?
The result should look like this:
L1 = [1,2,3,8,12,17]
Thank you !
Edit from comments:
I want to keep each element if it is only a certain distance (toleranz: 10 f.e.) distance away from the one before.
Your array is a list. You can use built in functions:
L1 = [1,2,3,-10,8,12,300,17]
min_val = min(L1) # -10
max_val = max(L1) # 300
p = list(filter(lambda x: min_val < x < max_val, L1)) # all x not -10 or 300
print(p) # [1, 2, 3, 8, 12, 17]
Doku:
min()
max()
filter()
If you want instead an incremental filter you go through your list of datapoints and decide if to keep or not:
delta = 10
result = []
last = L1[0] # first one as last value .. check the remaining list L1[1:]
for elem in L1[1:]:
if last-delta < elem < last+delta:
result.append(last)
last = elem
if elem-delta < result[-1] < elem+delta :
result.append(elem)
print(result) # [1, 2, 3, 8, 12, 17]
I need to get every 3rd value out of a list and add it to a new list.
This is what I have so far.
def make_reduced_samples(original_samples, skip):
skipped_list = []
for count in range(0, len(original_samples), skip):
skipped_list.append(count)
return skipped_list
skip is equal to 3
I get the indexes and not the value of the numbers in the list.
It gives me [0,3,6]. Which are the indexes in the list and not the value of the indexes.
The example I am given is:
In this list [12,87,234,34,98,11,9,72], you should get [12,34,9].
I cannot use skipped_list = original_samples[::3] in any way.
You need to append the value of the original_samples array at the index. Not the index (count) itself.
def make_reduced_samples(original_samples, skip):
skipped_list = []
for count in range(0, len(original_samples), skip):
skipped_list.append(original_samples[count])
return skipped_list
The correct, most pythonic, and most efficient way to do that is to use slicing.
lst = [12, 87, 234, 34, 98, 11, 9, 72]
skipped_list = lst[::3]
print(skipped_list) # [12, 34, 9]
If the step does not obey a linear relation (which it does here), then you could use a list-comprehension with enumerate to filter on the index.
skipped_list = [x for i, x in enumerate(lst) if i % 3 == 0]
print(skipped_list) # [12, 34, 9]
One liner:
skipped_list = [j for (i,j) in enumerate(original_samples, start=1) if i % 3 == 0]
Q)After executing the code Need to print the values [1, 12, 123, 2, 23, 3, 13], but iam getting [1, 12, 123, 2, 23, 3]. I have missing the letter 13. can any one tell me the reason to overcome that error?
def get_all_substrings(string):
length = len(string)
list = []
for i in range(length):
for j in range(i,length):
list.append(string[i:j+1])
return list
values = get_all_substrings('123')
results = list(map(int, values))
print(results)
count = 0
for i in results:
if i > 1 :
if (i % 2) != 0:
count += 1
print(count)
Pretty straight forward issue in your nested for loops within get_all_substrings(), lets walk it!
You are iterating over each element of your string 123:
for i in range(length) # we know length to be 3, so range is 0, 1, 2
You then iterate each subsequent element from the current i:
for j in range(i,length)
Finally you append a string from position i to j+1 using the slice operator:
list.append(string[i:j+1])
But what exactly is happening? Well we can step through further!
The first value of i is 0, so lets skip the first for, go to the second:
for j in range(0, 3): # i.e. the whole string!
# you would eventually execute all of the following
list.append(string[0:0 + 1]) # '1'
list.append(string[0:1 + 1]) # '12'
list.append(string[0:2 + 1]) # '123'
# but wait...were is '13'???? (this is your hint!)
The next value of i is 1:
for j in range(1, 3):
# you would eventually execute all of the following
list.append(string[1:1 + 1]) # '2'
list.append(string[1:2 + 1]) # '23'
# notice how we are only grabbing values of position i or more?
Finally you get to i is 2:
for j in range(2, 3): # i.e. the whole string!
# you would eventually execute all of the following
list.append(string[2:2 + 1]) # '3'
I've shown you what is happening (as you've asked in your question), I leave it to you to devise your own solution. A couple notes:
You need to look at all index combinations from position i
Dont name objects by their type (i.e. dont name a list object list)
I would try something like this using itertools and powerset() recipe
from itertools import chain, combinations
def powerset(iterable):
s = list(iterable)
return chain.from_iterable(combinations(s, r) for r in range(len(s) + 1))
output = list(map(''.join, powerset('123')))
output.pop(0)
Here is another option, using combinations
from itertools import combinations
def get_sub_ints(raw):
return [''.join(sub) for i in range(1, len(raw) + 1) for sub in combinations(raw, i)]
if __name__ == '__main__':
print(get_sub_ints('123'))
>>> ['1', '2', '3', '12', '13', '23', '123']
I have written this code which works but takes a very long time (~8hrs) to finish execution.
Wondering if it can be optimized to execute quicker.
The aim is to group a lots of items (x,y,z) coordinates based on their distance to one another. For example;
I would like to group them for a distance of +-0.5 in x, +-0.5 in y and +-0.5 in z, then the output from the data below would be [(0,3),(1),(2,4)...].
x y z
0 1000.1 20.2 93.1
1 647.7 91.7 87.7
2 941.2 44.3 50.6
3 1000.3 20.3 92.9
4 941.6 44.1 50.6
...
What I have done (and which works) is described below.
It compares the first row of the data_frame with the 2nd, 3rd, 4th .. until the end, and for each row, if the distance from x to x < +-0.5 and y to y < +-0.5 and z to z < +- 0.5 then the index is added to a list, group. If it doesn't then it compares the next row until reaching the end of the loop.
After each loop is complete the indexes which matched (stored in group), are added to another list, groups, as a set and then removed from the original list, a, and then next a[0] is compared and so on.
groups = []
group = []
data = [(x,y,z),(x,y,z),(etc)] # > 50,000 entries
data_frame = pd.DataFrame(data, columns=['x','y','z'])
a = list(i for i in range(len(data_frame)))
threshold = 0.5
for j in range(len(a) - 1) :
if len(a) > 0:
group.append(a[0])
for ii in range(a[0], len(data_frame) - 1):
if ((data_frame.loc[a[0],'x'] - data_frame.loc[ii,'x']) < threshold) and ((data_frame.loc[a[0],'y'] - data_frame.loc[ii,'y']) < threshold) and ((data_frame.loc[a[0],'z'] - data_frame.loc[ii,'z']) < threshold):
group.append(ii)
else:
continue
groups.append(set(group))
for iii in group:
if iii in a:
a.remove(iii)
else:
continue
group = []
else:
break
which returns something like this, for example;
groups = [{0}, {1, 69}, {2, 70}, {3, 67}, {4}, {5}, {6}, {7, 9}, {8}, {10}, {11}, {12}, 13}, {14, 73}, {15}, {16}, {17, 21, 74}, {18, 20}, {19}, {22, 23}]
Have made many edits to this question as it was not very clear. Hopefully makes sense now.
Below is an attempt using better logic 'O(NlogN)' which is much faster but doesn't return the correct answer. Have used the same +-0.5 for x,y,z.
Edit:
test_list = [(i,x,y,z), ... , (i,x,y,z)]
df3 = sorted(test_list,key=lambda x: x[1])
result = []
while df3:
if len(df3) > 1: ####added this because was crashing at the end of the loop
a = df3.pop(0)
alist=[a[0]]
while ((abs(a[1] - df3[0][1]) < 0.5) and (abs(a[2] - df3[0][2]) < 0.5) and (abs(a[3] - df3[0][3]) < 0.5)):
alist.append(df3.pop(0)[0])
if df3:
continue
else:
break
result.append(alist)
else:
result.append(a[0])
break
Since you are comparing each data point with every other one, your implementation has a worst time complexity of O(N!). A better way is to do a sorting first.
import random
df = [i for i in range(100)]
random.shuffle(df)
df2 = [(i,x) for i,x in enumerate(df)]
df3 = sorted(df2,key=lambda x: x[1])
df3
[(31, 0), (24, 1), (83, 2)......
Assuming now you want to group number that are +5/-5 into one list. You can then slice number into list based on a condition.
result = []
while df3:
a = df3.pop(0)
alist=[a[0]]
while a[1] + 5 >= df3[0][1]:
alist.append(df3.pop(0)[0])
if df3:
continue
else:
break
result.append(alist)
result
[[31, 24, 83, 58, 82, 35], [0, 65, 77, 41, 67, 56].......
Sorting takes O(NlogN) and a grouping basically takes linear time. So this would be much faster than N!