for each in Dti:
i = 0
for each in Dti[0]:
xbi[t][i] = Dti[t][i]
print(t)
i = i + 1
t = t + 1
this is just a test that I'm doing to figure out why my complicated code isn't working. I'm trying to iterate through a list and then each value in the list to set a new list of lists equal to that value. I know I could just set them equal to each other, but it needs to be done this way for my more complicated program. Any tips? I'm getting Dti[-1] for each xbi[t]. I've tried with while too and got the same results
Try something like this:
for t, D in enumerate(Dti)
for i, d in enumerate(D):
xbi[t][i] = d
print(t)
You can use slicing in assignments to replace one list's elements with the elements of another list:
for t, row in enumerate(Dti):
xbi[t][:] = row
Related
Can you explain these lines?
I can't understand what's happening in brackets (j,pbase).
mults = {}
if c in mults:
(j,pbase) = mults.pop(c)
Unpacking a tuple:
(j,pbase) = mults.pop(c)
Is the same as:
x = mults.pop(c)
j = x[0]
pbase = x[1]
a,b = something
This means something is a sequence of two values. a is assigned to the first value, and b is assigned to the second.
This is called tuple unpacking.
the python .pop() function will remove the item at that index and then return whatever was deleted. this means that the element of mults at index c will be stored within j and pbase. the way this is written would suggest that each element of the list is a tuple or such. this would mean that the first item goes in j and the second in pbase.
I want to delete some array from list. But I'm using wrong range.
At start the range is correct.
This should work, if string in variable result[b][2:3] then delete result[b]
for b in range(len(result)):
if 'FillLevel' in result[b][2:3]:
del result[b]
After that I have error: IndexError: list index out of range
I want to find this string and delete whole line (array):
V;4;FillLevel[1];CPUA.DB1610.0,I0,64;RW
V;4;FillLevel[2];CPUA.DB1610.0,I;RW
V;4;FillLevel[5];CPUA.DB1610.6,I;RW
V;4;FillLevel[6];CPUA.DB1610.8,I;RW
V;4;FillLevel[11];CPUA.DB1610.18,I;RW
Why this code:
print(result[4][2:3])
print(result[5][2:3])
print(result[6][2:3])
print(result[7][2:3])
print(result[8][2:3])
print(result[9][2:3])
print(result[10][2:3])
b = 0
while b < len(result):
if 'FillLevel' in result[b][2:3]:
del result[b]
del adress[b]
print('yes')
b += 1
Showing only once 'yes' ?
['FillLevel']
['FillLevel[1]']
['FillLevel[2]']
['FillLevel[3]']
['FillLevel[4]']
['FillLevel[5]']
['FillLevel[6]']
yes
The issue is that del result[b] changes the composition (and the length of) result, thereby interfering with your loop.
Perhaps the easiest way to fix this is by rephrasing your code as a list comprehension:
result = [r for r in result if 'FillLevel' not in r[2:3]]
Alternatively, you could fix it by iterating in reverse:
for b in range(len(result) - 1, -1, -1):
if 'FillLevel' in result[b][2:3]:
del result[b]
Let's say there are 10 items in the list.
Half-way through you delete one of the items; now there are 9 items in the list.
In the last cycle, your loop asks for the tenth item. My guess is that's where the index error is happening (though it could be due to the [2:3] call as well, depending on the contents of your list)
A more pythonic solution would be
result = [val for val in result if 'FillLevel' not in val[2:3]]
If you want to preserve the same list and parse it in the strait order you can use a while loop which evaluate the len(result) in each iteration
b = 0
while b < len(result) :
if 'FillLevel' in result[b][2:3]:
del result[b]
b += 1
for first
- it's mach easyer to iterate by list withot getting length, probably you are got an error coz length of list is changing during loop
for second
- you are trying to check 'FillLevel' in slice of string. slice return one character
- try to not midify your list but make new one with filtered items
like this:
new_list = []
for b in result:
if 'FillLevel' not in b:
new_list.append(b)
or check about List Comprehensions and type this:
[i for i in result if 'FillLevel' not in i]
I want to:
Take two inputs as integers separated by a space (but in string form).
Club them using A + B.
Convert this A + B to integer using int().
Store this integer value in list C.
My code:
C = list()
for a in range(0, 4):
A, B = input().split()
C[a] = int(A + B)
but it shows:
IndexError: list assignment index out of range
I am unable understand this problem. How is a is going out of the range (it must be starting from 0 ending at 3)?
Why it is showing this error?
Why your error is occurring:
You can only reference an index of a list if it already exists. On the last line of every iteration you are referring to an index that is yet to be created, so for example on the first iteration you are trying to change the index 0, which does not exist as the list is empty at that time. The same occurs for every iteration.
The correct way to add an item to a list is this:
C.append(int(A + B))
Or you could solve a hella lot of lines with an ultra-pythonic list comprehension. This is built on the fact you added to the list in a loop, but this simplifies it as you do not need to assign things explicitly:
C = [sum(int(item) for item in input("Enter two space-separated numbers: ").split()) for i in range(4)]
The above would go in place of all of the code that you posted in your question.
The correct way would be to append the element to your list like this:
C.append(int(A+B))
And don't worry about the indices
Here's a far more pythonic way of writing your code:
c = []
for _ in range(4): # defaults to starting at 0
c.append(sum(int(i) for i in input("Enter two space-separated numbers").split()))
Or a nice little one-liner:
c = [sum(int(i) for i in input("Enter two space-separated numbers").split()) for _ in range(4)]
huge = sum([x for key in G for (_,x) in G[key]]+1)
This is what I have so far, though its returning a type error, can only concatenate list (not "int") to list which I don't understand.
Basically Im dealing with a data structure something like
{1: [("A",2), ("B",3)]}
and so on like that, so that every key in the dictionary has a value which is a list of tuples, and the second item, index = 1 of each tuple are the values I want to sum, so in the example I gave:
huge = 5 # i.e. 2 + 3
Any advice??
>>> G = {1:[("A",2),("B",3)]}
>>> sum(y for v in G.itervalues() for (x, y) in v)
5
The errors comes from the expression [x for key in G for (_,x) in G[key]] + 1 which is trying to add a list and a number. That's a TypeError.
I think what you're looking for is something like this:
for itertools import chain
sum([v for _, v in chain.from_iterable(G.values())])
or with lazy evaluation:
sum(v for _, v in chain.from_iterable(G.itervalues()))
My python's rusty, but you have essentially
huge = sum([...list...] + 1)
I think it's complaining that you're adding 1 to a list. Did you mean:
huge = sum([...list...]) + 1
sum = 0
for key, item in data.iteritems():
for group in item:
sum += group[-1]
Should work just fine.
NOT everything has to be a list comprehension
I think we didn't have yet
sum(group[1] for value in data.itervalues() for group in value)
.
This may not be the most Pythonic, but it is straight-forward:
my_map = {1:[("A",1),("B",2)],2:[("C",3),("D",4)]}
total = 0
for k in my_map.keys():
this_list = my_map[k]
for this_tuple in this_list:
total += this_tuple[1]
print total
Are you saying you only want to sum up the tuples in the list G[1]? If so, this is what you were after:
huge = sum(x for _, x in G[1])
Note: You don't need to build a new list before summing it; leaving out the square brackets does it in one pass.
I have two arrays: array and least_common (filter array)
The following code iterates through array, checks for elements that match least_common, and if finds it, modifies it and appends it to a new array.
for i in range (len(array)):
for j in range(len(least_common)):
if array[i] is least_common[j][0]:
new_array.append ((array[i]) + (array[i] * (mod[1]/100)))
However, if the element in array does not match any of the elements in least_common I wan't to append it to new_array, then iterate to the next element in array to begin the checking process again.
This code is a bit wonky to me -- I think you want to start with something more like:
lookup = set([x[0] for x in least_common])
new_array = []
for elem in array:
if elem in lookup:
new_array.append(elem + (elem * (mod[1]/100)))
else:
new_array.append(elem)
In Python, what you are trying to do is done using lists. There is another separate data type called arrays, but that is for totally different purpose. Please don't confuse and use the proper terminology, list.
Lists can be iterated through. You need to not index the elements out of the list and then access them using the index. That is C or C++ way of doing things and not python.
You use a list or a dictionary called mod in your original code. It is a bad idea to override builtin names. I tried to understand what you are trying, came up with the following code. Take it further, but before that, I think some beginner tutorials might help you as well.
new_array = []
somevalue = 0.001
for elem in array:
for anotherelem in least_common:
if elem == anotherelem[0]:
new_array.append(elem + (elem * somevalue))
Keep track of whether you found a match using a boolean, which you set to False before each inner loop and set to True within your if. After each iteration, if it's still False it means you found no matches and should then do your appending.
You should also follow what #Andrew says and iterate over lists using for a in array:. If you need the index, use for i, a in enumerate(array):. And be aware that is is not the same as ==.
new_array = []
for array_item in array:
found = False
for least_common_item in least_common:
if array_item is least_common_item:
found = True
if not found:
new_array.append (array_item * (1 + mod[1]/100))
You can also greatly shorten this code using in if you meant to use == instead of is:
for array_item in array:
if array_item not in least_common:
new_array.append (array_item * (1 + mod[1]/100))
Why not this:
least_common_set = frozenset(x[0] for x in least_common)
for e in array:
if e is not in least_common_set:
new_array.append(e + (e * (mod[1]/100)))
If I understand correctly your problem, here is a possible solution:
for e in array:
for lc in least_common:
if e is lc[0]:
new_array.append(e + e * (md[1] / 100))
break
else:
new_array.append(e)
The else clause in the for loop is executed when the loop terminates through exhaustion of the list, but not when the loop is terminated by a break statement.
Note that there is no need to use range or len, in Python you can just iterate on the elements of a sequence without involving indexes - you may use enumerate for that, but in this case you don't need to. Also, please don't use built-in names such as mod for your variables: here, I have renamed your dictionary md.