大约有 18,000 项符合查询结果（耗时：0.0304秒） [XML]
How to import multiple .csv files at once?
...nto one file.
In Unix, if the files had no headers, then its as easy as:
m>cat m> *.csv > all.csv
or if there are headers, and you can find a string that matches headers and only headers (ie suppose header lines all start with "Age"), you'd do:
m>cat m> *.csv | grep -v ^Age > all.csv
I think in W...
What is the behavior difference between return-path, reply-to and from?
On our mailing applim>cat m>ion we are sending emails with the following header:
4 Answers
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Where are the PostgreSQL logs on macOS?
...
Just ask your database:
SELECT
*
FROM
pg_settings
WHERE
m>cat m>egory IN( 'Reporting and Logging / Where to Log' , 'File Lom>cat m>ions')
ORDER BY
m>cat m>egory,
name;
In my case, it's in "/Library/PostgreSQL/8.4/data/pg_log"
...
What is the difference between LR, SLR, and LALR parsers?
...ing that GLR parsers can parse any context free language, using more complim>cat m>ed machinery but exactly the same tables (including the smaller version used by LALR). This means that GLR is strictly more powerful than LR, LALR and SLR; pretty much if you can write a standard BNF grammar, GLR will pars...
(grep) Regex to match non-ASCII characters?
...e control bytes so strings can be the better option sometimes. For example m>cat m> test.torrent | perl -pe 's/[^[:ascii:]]+/\n/g' will do odd things to your terminal, where as strings test.torrent will behave.
share
|
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count the frequency that a value occurs in a dataframe column
...oupby.html
Also value_counts() as @DSM has commented, many ways to skin a m>cat m> here
In [38]:
df['a'].value_counts()
Out[38]:
b 3
a 2
s 2
dtype: int64
If you wanted to add frequency back to the original dataframe use transform to return an aligned index:
In [41]:
df['freq'] = df.groupb...
Opposite of %in%: exclude rows with values specified in a vector
A m>cat m>egorical variable V1 in a data frame D1 can have values represented by the letters from A to Z. I want to create a subset D2, which excludes some values, say, B, N and T. Basically, I want a command which is the opposite of %in%
...
Effects of changing Django's SECRET_KEY
...ed, the signature will fail to verify and the user will have to re-authentim>cat m>e.
For any users that have requested links for a password reset or a custom file download, those links will no longer be valid. The users would simply have to re-request those links.
Someone with more recent and/or salie...
Which are more performant, CTE or temporary tables?
....
Only 15 rows of the 1,000,000 randomly generated values match the predim>cat m>e but the expensive table scan happens 16 times to lom>cat m>e these.
This would be a good candidate for materializing the intermediate result. The equivalent temp table rewrite took 25 seconds.
INSERT INTO #T
SELECT *,
...
How to use Git and Dropbox together effectively?
...opbox bare repo from two machines at the same time. If it'll cause a modifim>cat m>ion in one of git's internal files, dropbox will show you there's a conflict -- but what do you do then? Just pick one of the versions, and then push again from both machines (one by one)?
– dubek
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