I'm trying to create a counter from 1 to n in an Arango query. Basically, I need to group objects by a number in that range, and return the count of the objects in each group. I had hoped creating a for loop would work, but it doesn't seem to be incrementing. I'm unsure about the syntax.
The two loop I've tried are:
FOR count IN [0,1,2,3]
and
FOR count IN 0..12
Those are the correct syntax to creating a counter loop.
The reason why it didn't seem to work for me was because I put the return statement containing the count variable in the sub-loop. It works when it is in the outer loop, like so:
FOR count IN 0..12
LET total = COUNT (
FOR v, e IN OUTBOUND "some-object" GRAPH "some-graph"
RETURN 1
)
RETURN {total: total, count: count}
Related
I'm struggling to grasp the problem here. I already tried everything but the issue persist.
Basically I have a list of random numbers and when I try to compare the vaalues inside loop it throws "IndexError: list index out of range"
I even tried with range(len(who) and len(who) . Same thing. When put 0 instead "currentskill" which is int variable it works. What I don't understand is why comparing both values throws this Error. It just doesn't make sence...
Am I not comparing a value but the index itself ???
EDIT: I even tried with print(i) / print(who[i] to see if everything is clean and where it stops, and I'm definitelly not going outside of index
who = [2, 0, 1]
currentskill = 1
for i in who:
if who[i] == currentskill: # IndexError: list index out of range
who.pop(i)
The problem is once you start popping out elements list size varies
For eg take a list of size 6
But you iterate over all indices up to len(l)-1 = 6-1 = 5 and the index 5 does not exist in the list after removing elements in a previous iteration.
solution for this problem,
l = [x for x in l if x]
Here x is a condition you want to implement on the element of the list which you are iterating.
As stated by #Hemesh
The problem is once you start popping out elements list size varies
Problem solved. I'm just popping the element outside the loop now and it works:
def deleteskill(who, currentskill):
temp = 0
for i in range(len(who)):
if who[i] == currentskill:
temp = i
who.pop(temp)
There are two problems in your code:
mixing up the values and indexes, as pointed out by another answer; and
modifying the list while iterating over it
The solution depends on whether you want to remove just one item, or potentially multiple.
For removing just one item:
for idx, i in enumerate(who)::
if i == currentskill:
who.pop(idx)
break
For removing multiple items:
to_remove = []
for idx, i in enumerate(who)::
if i == currentskill:
to_remove.append[idx]
for idx in reversed(to_remove):
who.pop(idx)
Depending on the situation, it may be easier to create a new list instead:
who = [i for i in who if i != currentskill]
Your logic is wrong. To get the index as well as the value, use the built-in function enumerate:
idx_to_remove = []
for idx, i in enumerate(who)::
if i == currentskill:
idx_to_remove.append[idx]
for idx in reversed(idx_to_remove):
who.pop(idx)
Edited after suggestion from #sabik
I want to make my algorithm more efficient via deleting the items it already sorted, but i don't know how I can do it efficiently. The only way I found was to rewrite the whole list.
l = [] #Here you put your list
sl = [] # this is to store the list when it is sorted
a = 0 # variable to store which numbers he already looked for
while True: # loop
if len(sl) == len(l): #if their size is matching it will stop
print(sl) # print the sorted list
break
a = a + 1
if a in l: # check if it is in list
sl.append(a) # add to sorted list
#here i want it to be deleted from the list.
The variable a is a little awkward. It starts at 0 and increments 1 by 1 until it matches elements from the list l
Imagine if l = [1000000, 1200000, -34]. Then your algorithm will first run for 1000000 iterations without doing anything, just incrementing a from 0 to 1000000. Then it will append 1000000 to sl. Then it will run again 200000 iterations without doing anything, just incrementing a from 1000000 to 1200000.
And then it will keep incrementing a looking for the number -34, which is below zero...
I understand the idea behind your variable a is to select the elements from l in order, starting from the smallest element. There is a function that does that: it's called min(). Try using that function to select the smallest element from l, and append that element to sl. Then delete this element from l; otherwise, the next call to min() will select the same element again instead of selecting the next smallest element.
Note that min() has a disadvantage: it returns the value of the smallest element, but not its position in the list. So it's not completely obvious how to delete the element from l after you've found it with min(). An alternative is to write your own function that returns both the element, and its position. You can do that with one loop: in the following piece of code, i refers to a position in the list (0 is the position of the first element, 1 the position of the second, etc) and a refers to the value of that element. I left blanks and you have to figure out how to select the position and value of the smallest element in the list.
....
for i, a in enumerate(l):
if ...:
...
...
If you managed to do all this, congratulations! You have implemented "selection sort". It's a well-known sorting algorithm. It is one of the simplest. There exist many other sorting algorithms.
I have two lists:
limits = [0.09090909,0.18181818,0.27272727]
res = [0.001,0.002,0.0923,0.0978,0.19374,0.21838]
limits list specifies the range and what I want to see how many values in res are less than for example the first value in limits and so on. And in a different list I want to store the last index of res whose value is less that 0.09, last index of res whose value is less than 0.1818 and so on.
So the result would be:
track = [1,3,5]
But my code is not doing that. My code so far is:
index = 0 ##this variable keeps track of where we are in limits list.
counter = 0 ## keeps track of indices in res list
for each_position in res:
if each_position <= limits[index]:
counter += 1
else:
track.append(counter)
index += 1
What I get from this code is [2,3] whereas the output should be [1,3,5].
Help would be appreciated.
Modify your loop a bit. Instead of looping through the results first, loop through the limits. Then for each limit check the results. Whenever you encounter a value in res larger than a limit, append the previous index in track list, break out of the inner loop and continue for remaining limits.
for limit in limits:
for index, value in enumerate(res):
if value > limit:
track.append(index - 1)
break
if len(res)-1 == index:
track.append(index)
Edit: my apologies. If you do not find a value in res that is larger than a limit, then store the last index of res.
How to find the minimum number of ways in which elements taken from a list can sum towards a given number(N)
For example if list = [1,3,7,4] and N=14 function should return 2 as 7+7=14
Again if N= 11, function should return 2 as 7+4 =11. I think I have figured out the algorithm but unable to implement it in code.
Pls use Python, as that is the only language I understand(at present)
Sorry!!!
Since you mention dynamic programming in your question, and you say that you have figured out the algorithm, i will just include an implementation of the basic tabular method written in Python without too much theory.
The idea is to have a tabular structure we will use to compute all possible values we need without having to doing the same computations many times.
The basic formula will try to sum values in the list till we reach the target value, for every target value.
It should work, but you can of course make some optimization like trying to order the list and/or find dividends in order to construct a smaller table and have faster termination.
Here is the code:
import sys
# num_list : list of numbers
# value: value for which we want to get the minimum number of addends
def min_sum(num_list, value):
list_len = len(num_list)
# We will use the tipycal dynamic programming table construct
# the key of the list will be the sum value we want,
# and the value will be the
# minimum number of items to sum
# Base case value = 0, first element of the list is zero
value_table = [0]
# Initialize all table values to MAX
# for range i use value+1 because python range doesn't include the end
# number
for i in range(1, value+1):
value_table.append(sys.maxsize);
# try every combination that is smaller than <value>
for i in range(1, value+1):
for j in range(0, list_len):
if (num_list[j] <= i):
tmp = value_table[i-num_list[j]]
if ((tmp != sys.maxsize) and (tmp + 1 < value_table[i])):
value_table[i] = tmp + 1
return value_table[value]
## TEST ##
num_list = [1,3,16,5,3]
value = 22
print("Min Sum: ",min_sum(num_list,value)) # Outputs 3
it would be helpful if you include your Algorithm in Pseudocode - it will very much look like Python :-)
Another aspect: your first operation is a multiplication with one item from the list (7) and one outside of the list (2), whereas for the second opration it is 7+4 - both values in the list.
Is there a limitation for which operation or which items to use (from within or without the list)?
I am trying to count the output of a regex search I am conducting on a dataset but for some reason my count is off by a lot. I was wondering what I am doing wrong and how I can get an official count. I should have around 1500 matches but I keep getting an error that says "'int' object is not iterable".
import re
with open ('Question 1 Logfile.txt' , 'r') as h:
results = []
count = []
for line in h.readlines():
m = re.search(r'(((May|Apr)(\s*)\w+\s\w{2}:\w{2}:\w{2}))', line)
t = re.search(r'(((invalid)(\s(user)\s\w+)))',line)
i = re.search(r'(((from)(\s\w+.\w+.\w+.\w+)))', line)
if m and t and i:
count += 1
print(m.group(1),' - ',i.group(4),' , ',t.group(4))
print(count)
You want to increment the number of times you satisfy a condition over a series of loop iterations. The confusion here seems to be how exactly to do that, and what variable to increment.
Here's a small example that captures the difficulty you've encountered, as described in OP and in OP comments. It's meant as a learning example, but it does also provide a couple of options for a solution.
count = []
count_int = 0
for _ in range(2):
try:
count += 1
except TypeError as e:
print("Here's the problem with trying to increment a list with an integer")
print(str(e))
print("We can, however, increment a list with additional lists:")
count += [1]
print("Count list: {}\n".format(count))
print("Most common solution: increment int count by 1 per loop iteration:")
count_int +=1
print("count_int: {}\n\n".format(count_int))
print("It's also possible to check the length of a list you incremented by one element per loop iteration:")
print(len(count))
Output:
"""
Here's the problem with trying to increment a list with an integer:
'int' object is not iterable
We can, however, increment a list with additional lists:
Count list: [1]
Most common is to increment an integer count by 1, for each loop iteration:
count_int: 1
Here's the problem with trying to increment a list with an integer:
'int' object is not iterable
We can, however, increment a list with additional lists:
Count list: [1, 1]
Most common is to increment an integer count by 1, for each loop iteration:
count_int: 2
It's also possible to check the length of a list you incremented
by one element per loop iteration:
2
"""
Hope that helps. Good luck learning Python!