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What is the difference between LR, SLR, and LALR parsers?
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SLR, LALR and LR parsers can all be implemented using exactly the same table-driven machinery.
Fundamentally, the parsing algorithm collects the next input token T, and consults the current state S (and associated lookahead, GOTO, and reduction tables...
Select rows which are not present in other table
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There are basically 4 techniques for this task, all of them standard SQL.
NOT EXISTS
Often fastest in Postgres.
SELECT ip
FROM login_log l
WHERE NOT EXISTS (
SELECT -- SELECT list mostly irrelevant; can just be empty in Postgr...
Python: How to get stdout after running os.system? [duplicate]
I want to get the stdout in a variable after running the os.system call.
6 Answers
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New to unit testing, how to write great tests? [closed]
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My tests just seems so tightly bound to the method (testing all codepath, expecting some inner methods to be called a number of times, with certain arguments), that it seems that if I ever refactor the method, the tests will fail even if the final behavior of the method did not change...
In C, how should I read a text file and print all strings
...igned.
If you want to read the file in chunks, but without dynamic memory allocation, you can do:
#define CHUNK 1024 /* read 1024 bytes at a time */
char buf[CHUNK];
FILE *file;
size_t nread;
file = fopen("test.txt", "r");
if (file) {
while ((nread = fread(buf, 1, sizeof buf, file)) > 0)
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What is the purpose of a self executing function in javascript?
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It's all about variable scoping. Variables declared in the self executing function are, by default, only available to code within the self executing function. This allows code to be written without concern of how variables are nam...
The static keyword and its various uses in C++
...that I find very confusing and I can never bend my mind around how its actually supposed to work.
9 Answers
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How to read data when some numbers contain commas as thousand separator?
...u can have read.table or read.csv do this conversion for you semi-automatically. First create a new class definition, then create a conversion function and set it as an "as" method using the setAs function like so:
setClass("num.with.commas")
setAs("character", "num.with.commas",
function(...
Create an array or List of all dates between two dates [duplicate]
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As for padding values with defaults in a time-series, you could enumerate all the dates in the full date-range, and pick the value for a date directly from the series if it exists, or the default otherwise. For example:
var paddedSeries = fullDates.ToDictionary(date => date, date => timeSeri...
Pandas: Looking up the list of sheets in an excel file
...eet_names attribute):
xl = pd.ExcelFile('foo.xls')
xl.sheet_names # see all sheet names
xl.parse(sheet_name) # read a specific sheet to DataFrame
see docs for parse for more options...
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