大约有 3,000 项符合查询结果（耗时：0.0268秒） [XML]
Count how many records are in a CSV Python?
...han Martijn Pieters's. For 10M lines, %time sum(1 for row in open("df_data_raw.csv")) cost 4.91s while %time len(open("df_data_raw.csv").readlines()) cost 14.6s.
– Pengju Zhao
May 13 '18 at 9:13
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Finding ALL duplicate rows, including “elements with smaller subscripts”
...st ran a test and found I was wrong: x <- c(1:9, 7:10, 5:22); y <- c(letters, letters[1:5]); test <- data.frame(x, y); test[duplicated(test$x) | duplicated(test$x, fromLast=TRUE), ] Returned all three of he copies of 7, 8, and 9. Why does that work?
– JoeM05
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Is it possible to implement a Python for range loop without an iterator variable?
...ing to Python grammar, it is an acceptable variable name:
identifier ::= (letter|"_") (letter | digit | "_")*
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Load different colorscheme when using vimdiff
...ally beautiful.
curl -fLo ~/.vim/colors/molokai.vim --create-dirs https://raw.githubusercontent.com/tomasr/molokai/master/colors/molokai.vim
curl -fLo ~/.vim/colors/github.vim --create-dirs https://raw.githubusercontent.com/endel/vim-github-colorscheme/master/colors/github.vim
Put the following c...
Where does 'Hello world' come from?
... example
program from that book prints "hello,
world" (without capital letters or
exclamation mark), and was inherited
from a 1974 Bell Laboratories internal
memorandum by Brian Kernighan,
Programming in C: A Tutorial, which
contains the first known version:
main() {
printf("...
Read a variable in bash with a default value
...e to simplify following if
PROCEED="${PROCEED,,}"
# condition for specific letter
if [ "${PROCEED}" == "q" ] ; then
echo "Quitting"
exit
# condition for non specific letter (ie anything other than q/y)
# if you want to have the active 'y' code in the last section
elif [ "${PROCEED}" != "y" ] ; t...
What are the main performance differences between varchar and nvarchar SQL Server data types?
...re fixed length, human readable, and well, standard :) use CHAR(2) for two letter codes and CHAR(3) if using 3 letter codes. And consider using a binary Collation such as Latin1_General_100_BIN2.
If storing postal codes (i.e. zip codes), use VARCHAR since it is an international standard to never use...
Replace a value in a data frame based on a conditional (`if`) statement
...in the arguments to data.frame()
Option 1:
junk <- data.frame(x = rep(LETTERS[1:4], 3), y =letters[1:12], stringsAsFactors=FALSE)
junk$nm[junk$nm == "B"] <- "b"
Option 2:
levels(junk$nm) <- c(levels(junk$nm), "b")
junk$nm[junk$nm == "B"] <- "b"
junk
...
Uri to default sound notification?
...tomSoundUri = Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.twirl);
Source of notification sound (I renamed to "twirl" and placed in
res->raw folder)
https://notificationsounds.com/message-tones/twirl-470
Notification builder:
NotificationCompat.Builder mBuilder =
...
Preserve Line Breaks From TextArea When Writing To MySQL
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You should always store data raw in the database. Then convert and sanitize the data before you display it.
– Edward
Oct 31 '18 at 15:37
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