I am trying to create a new list via a list comprehension but want those new values to be included in an existing list.
More specifically, I am try to create a string out of the date and will have some string formatting between the values ( a dash - ). The existing list will be a template if you will with the dash.
Here is what I have so far:
{Date, Time} = erlang:universaltime().
DateList = tuple_to_list(Date).
DateListString = [ integer_to_list(X) || X < DateList ].
DateListStringConcatenate = lists:flatten(DateListString).
The result should be something along
"20101121"
But, what I want is
"2010-11-21"
So I am thinking about the DateListString comprehension "comprehending" to an existing list with "-" after the first and second element.
Any suggestions accompanied with concrete code samples much appreciated.
1> {{Y,M,D},_} = erlang:universaltime().
{{2010,11,21},{16,42,56}}
2> lists:flatten(io_lib:format("~p-~p-~p", [Y,M,D])).
"2010-11-21"
If you really want it in a list comprehension then you could do the following:
{Date, Time} = erlang:universaltime().
DateList = tuple_to_list(Date).
DateListString = [ [$- | integer_to_list(X)] || X <- DateList ].
[_ | DateListStringConcatenate] = lists:flatten(DateListString).
Roberto's is a better/more efficient solution to this but in case you wondered how you might do it with a list comprehension this would be one way.
This is a possible solution, but I feel that it is not an elegant one. Also, it does not use list comprehension.
1> {Date, Time} = erlang:universaltime().
{{2010,11,21},{14,51,23}}
2> DateList = tuple_to_list(Date).
[2010,11,21]
3> DateListString = lists:zipwith(fun(X,Y) -> integer_to_list(X) ++ Y end, DateList, ["-","-",""]).
["2010-","11-","21"]
4> DateListStringConcatenate = lists:flatten(DateListString).
"2010-11-21"
Related
I have a list of tuples (lot):
lot = [('490001', 'A-ARM1'),
('490001', 'A-ARM2'),
('490002', 'B-ARM3')]
Subsequently, I loop through every second tuple element and wish to replace every 'A-' and 'B-' characters by a dictionary value:
from more_itertools import grouper
dict = {'A-': 'ZZ', 'B-': 'XX'}
for el1, el2 in lot:
for i, j in grouper(el2, 2):
if i+j in dict:
lot2 = [ (el2.replace( (i+j), dict[i+j] )) for el1, el2 in lot ]
print(lot2)
After 'lot2 = ' something is going wrong, my output is
['A-ARM1', 'A-ARM2', 'XXARM3'] instead of [ZZARM1', 'ZZARM2', 'XXARM3']
Can anyone give me a hint on how to resolve this? Also, if you think I can write this more elegantly, feel free to let me know. I'm eager to learn. Any help is greatly appreciated.
This might not be the shortest solution, but it should work:
lot2 = []
for el1, el2 in lot:
lookup = el2[:2]
if lookup in dict:
lot2.append(dict[lookup] + el2[2:])
else:
lot2.append(el2)
This is my code to create lists, but its so brutal and inelegant, you guys have some idea to make it much smoother?
Thing is, I want to write code, where you could create your own lists, choose how many of them you want to create and how much items each should have - NOT using while loop. I can manage creating certain number of lists by inputing the range in for loop (number_of_lists)
i = 0
number_of_lists = input('How many lists you want to make? >')
for cycle in range(number_of_lists): #this was originaly range(3),
item1 = raw_input('1. item > ') #and will only work now pro-
item2 = raw_input('2. item > ') #perly, if n_o_l is exact. 3
item3 = raw_input('3. item > ')
#everything is wrong with this
print "-------------------" #code, i need it much more au-
#tonomous, than it is now.
if i == 0:
list1 = [item1, item2, item3]
if i == 1:
list2 = [item1, item2, item3]
if i == 2:
list3 = [item1, item2, item3]
i += 1
print list1
print list2
print list3
Thing is I also want to avoid all that 'if i == int' thing.
Now it will only create 3 lists, right, because instead of number_of_lists i originally used integer 3 to make 3 lists.
Now you see my problem I hope. I need to create new lists from input and name them if possible, so instead of list1 i can name it DOGS or w/e.
I need it all much more simple and interconnected, I hope you understand my problem and maybe have some smooth solution, thanks :)
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Ok, I think I got it now - this is new version, doing pretty much what i want it to do:
number_of_lists = input('How many lists you want to make? >')
allItems = []
for cycle in range(int(number_of_lists)):
items = []
number_of_items = input('How much items in this list? >')
for i in range(int(number_of_items)):
item = raw_input(str(i+1) + ". item > ")
items.append(item)
allItems.append(items)
print("-------------------")
print allItems
If anyone has idea how to make this more effective and clear, let me know here! :) thanks for help guyz
You can add your lists to another list, that way it's dynamic like you want. Example below:
number_of_lists = input('How many lists you want to make? >')
allItems = []
for cycle in range(int(number_of_lists)):
items = []
for i in range(1, 4):
item = input(str(i) + ".item > ")
items.append(item)
allItems.append(items)
print("-------------------")
for items in allItems:
for item in items:
print(item)
print("-------------")
You'd still need to check if number_of_lists is an int before parsing it into an int. If the user types a letter it will throw an error.
I have a list of unicode elements and I'm trying to remove all integer numbers from It.
My code is:
List = [u'123', u'hello', u'zara', u'45.3', u'pluto']
for el in List:
if isinistance(el, int):
List.remove(el)
The code doesn't work, It give me the same list with u'123' include.
What i need is this:
List = [ u'hello', u'zara', u'45.3', u'pluto']
Can somebody hel me?
You list consists of unicode strings which are no instances of int obviously. You can try converting them to int in a helper function and use this as a condition to remove them/ to construct a new list.
def repr_int(s):
try:
int(s)
return True
except ValueError:
return False
original_list = [u'123', u'hello', u'zara', u'45.3', u'pluto']
list_with_removed_ints = [elem for elem in original_list if not repr_int(elem)]
I have a couple List<string>s, with the format like this:
List 1 List 2 List 3
1 A One
2 B Two
3 C Three
4 D Four
5 E Five
So in code form, it's like:
List<string> list1 = {"1","2","3","4","5"};
List<string> list2 = {"A","B","C","D","E"};
List<string> list3 = {"One","Two","Three","Four","Five"};
My questions are:
How do I transfom those three lists to a CSV format?
list1,list2,list3
1,A,one
2,b,two
3,c,three
4,d,four
5,e,five
Should I append , to the end of each index or make the delimeter its own index within the multidimensional list?
If performance is your main concern, I would use an existing csv library for your language, as it's probably been pretty well optimized.
If that's too much overhead, and you just want a simple function, I use the same concept in some of my code. I use the join/implode function of a language to create a list of comma separated strings, then join that list with \n.
I'm used to doing this in a dynamic language, but you can see the concept in the following pseudocode example:
header = {"List1", "List2", "List3"}
list1 = {"1","2","3","4","5"};
list2 = {"A","B","C","D","E"};
list3 = {"One","Two","Three","Four","Five"};
values = {header, list1, list2, list3};
for index in values
values[index] = values[index].join(",");
values = values.join("\n");
I have a question about iterating through lists.
Let's say i have list of maps with format
def listOfMaps = [ ["date":"2013/05/23", "id":"1"],
["date":"2013.05.23", "id":"2"],
["date":"2013-05-23", "id":"3"],
["date":"23/05/2013", "id":"4"] ]
Now i have a list of two patterns (in reality i have a lot more :D)
def patterns = [
/\d{4}\/\d{2}\/\d{2}/, //'yyyy/MM/dd'
/\d{4}\-\d{2}\-\d{2}/ //'yyyy-MM-dd'
]
I want to println dates only with the "yyyy/MM/dd" and "yyyy-MM-dd" format so i have to go through the lists
for (int i = 0; i < patterns.size(); i++) {
def findDates = listOfMaps.findAll{it.get("word") ==~ patterns[i] ?
dateList << it : "Nothing found"}
}
but i have a problem with this way. What if the list "listOfMaps" gonna be huge? It will take a lot of time to find all patters because this code will have to go through the whole list of patters and the same amount of time it will have to go through list of maps wich in case of huge lists might take a long while :). I tried with forEach inside the findAll clousure it does not work.
So my question is is there any way to go through the list of patterns inside the findAll clousure? For instance sth like this in pseudocode
def findDates = listOfMaps.findAll{it.get("word") ==~ for(){patterns[i]} ? : }
so in that case it goes only once through the listOfMaps list and it iterates through patterns(which always is way way way way smaller than listOfMaps).
I might have an idea to create a function that returns the instance of list, but i'm struggling to implement this :).
Thanks in advance for response.
You could do:
def listOfMaps = [ [date:"2013/05/23", id:"1"],
[date:"2013.05.23", id:"2"],
[date:"2013-05-23", id:"3"],
[date:"23/05/2013", id:"4"] ]
def patterns = [
/\d{4}\/\d{2}\/\d{2}/, //'yyyy/MM/dd'
/\d{4}\-\d{2}\-\d{2}/ //'yyyy-MM-dd'
]
def foundRecords = listOfMaps.findAll { m ->
patterns.find { p ->
m.date ==~ p
}
}