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Unique constraint that allows empty values in MySQL
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@MianAnjum bolded: CREATE TABLE table (key int(11) NOT NULL AUTO_INCREMENT, field tinyint(1) DEFAULT NULL)
– Paul Nowak
Sep 19 '17 at 19:45
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Is R's apply family more than syntactic sugar?
... This is a little off topic, but for this specific example, data.table is even faster and I think "easier". library(data.table) dt<-data.table(X,Y,Z,key=c("Y,Z")) system.time(dt[,list(X_mean=mean(X)),by=c("Y,Z")])
– dnlbrky
Feb 22 '13 at 4:01
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How to disable margin-collapsing?
...collapsing") entail using a 1px border or 1px padding. I find this unacceptable: the extraneous pixel complicates calculations for no good reason. Is there a more reasonable way to disable this margin-collapsing?
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How to understand Locality Sensitive Hashing?
...akes as input a set of documents/images/objects and outputs a kind of Hash Table.
The indexes of this table contain the documents such that documents that are on the same index are considered similar and those on different indexes are "dissimilar".
Where similar depends on the metric system and ...
How can I run a PHP script in the background after a form is submitted?
...s enough to cause it takes upwards of a minute to cycle through the entire table of subscribers and send out 150+ emails. (The emails are being sent individually as requested by the system administrators of our email server because of mass email policies.)
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Prevent row names to be written to file when using write.csv
..., "t.csv")
If you need to write big data out, use fwrite() from the data.table package. It's much faster than both write.csv and write_csv
# install.packages('data.table')
library(data.table)
fwrite(t, "t.csv")
Below is a benchmark that Edouard published on his site
microbenchmark(write.csv(d...
How to get image height and width using java?
... byte: H is first four bits and V is second four bits
o Quantization table number-- one byte
The H and V sampling factors dictate the final size of the component they are associated with. For instance, the color space defaults to YCbCr and the H and V sampling factors for each component, Y, C...
What MIME type should I use for CSV?
... Jun 27 '12 at 13:31
LittleBobbyTables - Au Revoir
29.5k1212 gold badges9393 silver badges110110 bronze badges
answered Aug 16 '11 at 9:24
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How to find out what character key is pressed?
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Try:
<table>
<tr><td>Key:</td><td id="key"></td></tr>
<tr><td>Key Code:</td><td id="keyCode"></td></tr>
<tr><td>Event Code:</td><td ...
Resize image in the wiki of GitHub using Markdown
...inside the wiki). Additionally, I had to add one or two images inside of a table. The pipe character was giving me grief because of typical table formatting in markdown. Escaping the pipe inside a table cell is still valid: [[ http://url.to/img.png \| height=48px]].
– DanMad
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