Assume that the input file "input.txt" looks like the following:
Sam 92
Zoe 80
Ted 45
Sue 74
What is the output of the following code?
x = ""
infile = open("input.txt", "r")
for line in infile:
parts = line.split()
x += parts[1].strip()
print(x)
Lori, welcome to SO! Please read the community guidelines on how to use the different tools just above the text editor to make your question clearly readable by other users.
In regard to your question, let's break it down:
1 x = ""
2 infile = open("input.txt","r")
3 for line in infile.readlines():
4 parts = line.split()
5 x += parts[1].strip()
6 print x
Line 2 calls the open() method which creates a new object through which you can read a file (notice the "r" flag which means the file can only be read). Then, a for loop is executed for each line in the file (there's an error in line 3, I've added the readlines() method call for it to work).
For each line in the file, split the line using space as a delimiter (meaning that a list is created where each element is a substring between two spaces). Then, concatenate the second element in the list (this will be the number next to each name) to the variable x, stripping any unnecessary white spaces before and after the number. Then, when you're done, print x. This will print all the numbers, one after another, without any spacing, like so: 92804574
Related
yy and p should copy and paste 1 line of text.
But I have to go back and delete the original line.
:2,5m10
should move lines from 2 to 5 to line 10. however I need to enable :set number
to see what lines I am moving
I would like to move just 1 line of text, sort of like yy+p and not use :2,3m10
to move just one line.
Is there something like mm+p ?
so it copies the current line into buffer and deletes the line and you p paste it where you want ?
:3m . moves line 3 to your current line.
Above line does the function I want. Can I set a key mapping so
that "mm" replaces ":3m." ? I find it easier to type. TIA
What you're describing is the default behaviour when using dd -it deletes a
line into the buffer and p will paste it.
So dd and p works.
If you're new to vim, then it might seem a little strange that 'yanking' (with
y) and 'deleting' (with d) both copy to the buffer, given the 'cut', 'copy'
and 'paste' behaviours of most other editors.
You can read more about it with :help change.txt and in particular :help registers.
Also, since you say you need to enable :set number, I wonder if you've come
across :set relativenumber? This is very useful - in the example below, the
numbers would look this way if the your cursor was on the line with
'demonstrate':
3 This is just
2 a small
1 example to
0 demonstrate
1 how relative
2 numbers can
3 be useful
Thus if you wanted to move the line 'a small' below the line with 'numbers
can', you could use the relative line numbers to know that 2k would put the
cursor on the line you want, where you'd hit dd, then you'd have this
situation (the deleted line is now in the buffer:
1 This is just
0 example to
1 demonstrate
2 how relative
3 numbers can
4 be useful
Then you can do 3j to move to the 'numbers can' line, and hit p. So
relative numbers are a nice way to move quickly to lines you can see. Also,
just for completeness, you can use relative numbers in a similar way on the
command line::-2m+3 (although I know this isn't what you're after). You can
even set both relative number and set number at the same time, in which case
it's like in the example above, only you have the absolute line number
displayed on the current line instead of a zero.
I need to be able to parse 2 different types of CSVs with read_csv, the first has ;-separated values and the second has ,-separated values. I need to do this at the same time.
That is, the CSV can have this format:
some;csv;values;here
or this:
some,csv,values,here
or even mixed:
some;csv,values;here
I tried many things like the following regex but nothing worked:
data = pd.read_csv(csv_file, sep=r'[,;]', engine='python')
Am I doing something wrong with the regex?
Instead of reading from a file, I ran your code sample
reading from a string:
txt = '''C1;C2,C3;C4
some;csv,values;here
some1;csv1,values1;here1'''
data = pd.read_csv(io.StringIO(txt), sep='[,;]', engine='python')
and got a proper result:
C1 C2 C3 C4
0 some csv values here
1 some1 csv1 values1 here1
Note that the sep parameter can be even an ordinary (not raw) string,
because it does not contain any backslashes.
So your idea to specify multiple separators as a regex pattern is OK.
The reason that your code failed is probably an "inconsistent" division of
lines into fileds. Maybe you should ensure that each line contains the
same number of commas and semi-colons (at least not too many).
Look thoroughly at your stack trace. There should include some information
about which line of the source file caused the problem.
Then look at the indicated line and correct it.
Edit
To look what happens in a "failure case", I changed the source string to:
txt = '''C1;C2,C3;C4
some;csv,values;here
some1;csv1,values1;here1
some2;csv2,values2;here2,xxxx'''
i.e. I added one line with 5 fields (one too many).
Then execution of the above code results in an error message:
ParserError: Expected 4 fields in line 4, saw 5. ...
Note words in line 4, precisely indicating the offending input line
(line numbers starts from 1).
I'm trying to use VHDL to read from a file that can have different formats. I know you're supposed to use the following two lines of code to read a line at a time, the read individual elements in that line.
readline(file, aline);
read(aline, element);
However my question is what will read(aline, element) return into element? What will it return if the line is empty? What will it return if I've used it let's say 5 times and my line only has 4 characters?
The reason I want to know is that if I am reading a file with an arbitrary number of spaces between valid data, how do I parse this valid data?
The file contains ASCII characters separated by arbitrary amounts of white space (any number of spaces, tabs, or new lines). If the line starts with a # that line is a comment and should be ignored.
Outside of these comments, the first part of the file contains characters that are only letters or numbers in combinations of variable size. In other words this:
123 ABC 12ABB3
However, the majority of the file (after a certain number of read words) will be purely numbers of arbitrary length, separated by an arbitrary amount of white space. In other words, the second part of the file is this:
255 0 2245 625 430
2222 33 111111
and I must be able to parse these numbers (and interpret them as such) individually.
As mentioned in the comments, all the read procedures in std.textio and ieee.std_logic_textio skip over leading spaces apart from the character and string versions (because a space is as much a character as any other).
You can test whether a line variable (the buffer) is empty like this:
if L'length > 0 then
where L is your line variable. There is also a set of overloaded read procedures with an extra status output:
procedure read (L : inout LINE;
VALUE: out <type> ;
GOOD : out BOOLEAN);
The extra output - GOOD - is true if the read was successful and false if it wasn't. The advantage of these if that the read is unsuccessful, the simulation does not stop (as it does with the regular procedures). Also, with the versions in std.textio, if the read is unsuccessful, the read is non-destructive (ie whatever you were trying to read remains in the buffer). This is not the case with the versions in ieee.std_logic_textio, however.
If you really do not know what format you are trying to read, you could read the entire line into a string, like this:
variable S : string(1 to <some big number>);
...
readline(F, L);
assert L'length < S'length; -- make sure S is big enough
S := (others => ' '); -- make sure that the previous line is overwritten
if L'length > 0 then
read(L, S(1 to L'length);
end if;
The line L is now in the string S. You can then write some code to parse it. You may find the type attribute 'value useful. This converts a string to some type, eg
variable I : integer;
...
I := integer'value(S(12 to 14));
would set integer I to the value contained in elements 12 to 14 of string S.
Another approach, as suggested by user1155120 below, is to peek at the values in the buffer, eg
if L'length > 0 then -- check that the L isn't empty, otherwise the next line blows up
if L.all(1) = '#' then
-- the first character of the line is a '#' so the line must be a comment
How can I get an input from user in Lua (like scanf in C)?
For example, the program ask user his name, then he writes his name, then the program will output his name.
Use io.read() Beware that the function can be customised with different parameters. Here are some examples.
s = io.read("*n") -- read a number
s = io.read("*l") -- read a line (default when no parameter is given)
s = io.read("*a") -- read the complete stdin
s = io.read(7) -- read 7 characters from stdin
x,y = io.read(7,12) -- read 7 and 12 characters from stdin and assign them to x and y
a,b = io.read("*n","*n") -- read two numbers and assign them to a and b
The simplest input can be retrieved using io.read(). This will read a single line from the standard input (usually the keyboard, but can be redirected e.g. from file).
You can use it like this:
io.write('Hello, what is your name? ')
local name = io.read()
io.write('Nice to meet you, ', name, '!\n')
io.read() is just a shortcut for io.input():read(), similarly io.write() is a shortcut to io.output():write(). See the API for read() here.
Notice that io.write() will not auto-terminate your line like print() does.
I'm trying to parse a text file. First I plan on extrcating each line, then extracting each field by searching for a tasb.
When I use InStr to sercah for a \r (return for end of line) or \t (for tab) I always get a zero. But if I put in a visable letter such as a I got a 5.
also I tried /r, /n and \n all return a zero.
The file looks as follows:
ID Name
1 Patient
2 Bed
3 PatientSet
4 BedSet
5 TriggerSet
6 Triggering
7 Panel
the code
fileReader = My.Computer.FileSystem.ReadAllText("D:\BW\bwdatabase\ContextType.txt")
MsgBox(fileReader)
Str = fileReader
i = InStr(Str, "\r") // i uis zero
l = Mid(Str, 0, i - 1) // so this crashes becouse index is -1
MsgBo
Look into using the Microsoft.VisualBasic.FileIO.TextFieldParser class. It will do all the heavy lifting for you.
"\r" does not work in VB. For \r, use vbCr; for \n, use vbLf.