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Warning message: In `…` : invalid factor level, NA generated
...e" variable was made a factor and "lunch" was not a defined level. Use the stringsAsFactors = FALSE flag when making your data frame to force "Type" to be a character.
> fixed <- data.frame("Type" = character(3), "Amount" = numeric(3))
> str(fixed)
'data.frame': 3 obs. of 2 variables:
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How to add leading zeros?
...x <- 10 ^ (0:5)
paste (and it's variant paste0) are often the first string manipulation functions that you come across. They aren't really designed for manipulating numbers, but they can be used for that. In the simple case where we always have to prepend a single zero, paste0 is the best s...
How dangerous is it to access an array out of bounds?
...: if you have an fixed size array, and use strcpy() to put a user-supplied string there, the user can give you a string that overflows the buffer and overwrites other memory locations, including code address where CPU should return when your function finishes.
Which means your user can send you a s...
What is the difference between atomic and critical in OpenMP?
...(on top of the inherent cost of serialization).
(In addition, in OpenMP all unnamed critical sections are considered identical (if you prefer, there's only one lock for all unnamed critical sections), so that if one thread is in one [unnamed] critical section as above, no thread can enter any [un...
The 3 different equals
...ot of same data type';
}
// here $a is of type int whereas $b is of type string. So here the output
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Android emulator shows nothing except black screen and adb devices shows “device offline”
...tor comes up on the screen. But even after waiting for as long as 2-3 hrs, all it shows is a black screen. Not even the android home screen or the android logo. Just a black screen. And while initially "adb devices" shows the emulator as offline.after 2-3 minutes the list of attached devices becomes...
Python Regex instantly replace groups
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Have a look at re.sub:
result = re.sub(r"(\d.*?)\s(\d.*?)", r"\1 \2", string1)
This is Python's regex substitution (replace) function. The replacement string can be filled with so-called backreferences (backslash, group number) which are replaced with what was matched by the groups. Groups ar...
Getting new Twitter API consumer and secret keys
...term "API key" usually refers to what's called an OAuth consumer key. This string identifies your application when making requests to the API. In OAuth 1.0a, your "API keys" probably refer to the combination of this consumer key and the "consumer secret," a string that is used to securely "sign" you...
increment date by one month
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It didn't work with this string: "2014-06-19 15:00:19"
– Meetai.com
Jun 22 '14 at 2:53
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Test if a string contains any of the strings from an array
How do I test a string to see if it contains any of the strings from an array?
14 Answers
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