Problem 1. Write a main()
function that loads a list of strings and prints them sorted, ignoring their character case (so called case insensitive comparison).
For example:
"John" < "alien"
, because all capital letters come before all lower case letters;"John" > "alien"
, because the case is ignored, so it is the same as "john" > "alien"
).Note: The original strings in the list should not be altered in any way!
Hint: Using str.lower()
in combination with the key
argument of sort
and a lambda
-function might help you.
Problem 2. Write a function del_double(s, char_del, char_double)
that returns a new string obtained from s
by removing all the occurrences of the character char_del
and doubling all the occurrences of the character char_double
. If char_del
is not given, nothing should be removed. Similarly, if char_double
is not given, nothing should be doubled.
For example,
del_double("abcdbacabcd", "b", "d")
should return "acddacacdd"
,del_double("abcdbacabcd", "b")
should return "acdacacd"
,del_double("abcdbacabcd", char_double="d")
should return "abcddbacabcdd"
,del_double(s)
should return a copy of s
.If char_del == char_double
, then no doubling will take place because the deletions will remove all the occurences of char_del
(which are the same as the occurences of char_double
).
Note: In del_double
, you may assume that len(char_del) == len(char_double) == 1
, but make sure that this is correct when loading the data.
Hint: Write an auxiliary function that will take three characters c
, c_del
, and c_double
, and return
c == c_del
,c
if c == c_double
,c
otherwise.Then use this function in a list comprehension that traverses through the string s
.
Problem 3. Write a function time_diff(t1, t2)
that returns the absolute time difference between the times t1
and t2
. Each of them is given as a string formated either as hh:mm:ss
or as mm:ss
. The returned difference should have the same format (hh
part should be omitted if it equals zero), with each part taking up at least two digits.
For example,
time_diff("17:19:23", "13:11:7")
should return "04:08:16"
;time_diff("13:11:7", "17:19:23")
should also return "04:08:16"
(because the function returns the absolute time difference);time_diff("17:19:23", "11:7")
should return "17:08:16"
;time_diff("17:19:23", "17:11:7")
should return "08:16"
.Hint: Write two auxiliary functions, str2time
and time2str
, that will convert the string of the described format to the number of seconds since the beginning of the day (3600*hh+60*mm+ss
) and vice versa.
Problem 4. Write a function remove(s, chrs, case_sensitive)
that returns a string obtained from s
by removing all the characters present in chrs
. The parameter case_sensitive
is Boolean; if it is True
, the matching is case sensitive; otherwise it is insensitive. If the function is invoked with only two arguments, the match should be case sensitive.
For example, remove(s, "0123456789")
would return the copy of s
without any digits it may have had. So, remove("a12b0 c", "0123")
would return "ab c"
. Similarly, remove(s, "A")
would return a copy of s
without upper case letters "A
" (but all lower case letters "a
" would remain intact). However, remove(s, "A", False)
would return a copy of s
without any letters "A
", lower case or upper case.
Preferably, use a generator expression to create this new string.
Program 5. Write a function load_a_list_of_ints_as_a_string()
that loads a list of integers with a singe call to input
. Assume that the it will be given in the form "x1,x2,...,xn"
. For example, "17,-19,23"
(without spaces or any characters other than a single comma between each two neighbour integers).
Write a main()
function that uses this function to load a list of integers, and print it sorted in a descended order.