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Is char signed or unsigned by default?
In the book "Complete Reference of C" it is mentioned that char is by default unsigned.
7 Answers
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How to use GROUP BY to concatenate strings in SQL Server?
...1]','VARCHAR(MAX)')
,1,2,'') AS NameValues
FROM #YourTable Results
GROUP BY ID
DROP TABLE #YourTable
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Invalid default value for 'create_date' timestamp field
...d].
and set sql_mode to the following:
NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
Save and then restart mysql service by doing:
sudo service mysql restart
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How are feature_importances in RandomForestClassifier determined?
... impurity" and is defined as the total decrease in node impurity (weighted by the probability of reaching that node (which is approximated by the proportion of samples reaching that node)) averaged over all trees of the ensemble.
In the literature or in some other packages, you can also find featur...
typedef fixed length array
...that it's an array type. If used as a function argument, it will be passed by reference, not by value, and the sizeof for it will then be wrong.
A better solution would be
typedef struct type24 { char x[3]; } type24;
You probably also want to be using unsigned char instead of char, since the lat...
Querying DynamoDB by date
...in to find the data.
You can of course perform a scan operation to filter by the date value, however this would require a full table scan, so it is not ideal.
If you need to perform an indexed lookup of records by time across multiple primary keys, DynamoDB might not be the ideal service for you t...
Explode string by one or more spaces or tabs
How can I explode a string by one or more spaces or tabs?
10 Answers
10
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Scala downwards or decreasing for loop?
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scala> 10 to 1 by -1
res1: scala.collection.immutable.Range = Range(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
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Change timestamps while rebasing git branch
...-date-is-author-date "[...]allows the user to lie about the committer date by using the same value as the author date" while --ignore-date "[...]allows the user to lie about the author date by using the same value as the committer date".
– Enrico Campidoglio
Fe...
Aggregate / summarize multiple variables per group (e.g. sum, mean)
....table/wiki
library(data.table)
df2 <- setDT(df1)[, lapply(.SD, sum), by=.(year, month), .SDcols=c("x1","x2")]
setDF(df2) # convert back to dataframe
Using the plyr package
require(plyr)
df2 <- ddply(df1, c("year", "month"), function(x) colSums(x[c("x1", "x2")]))
Using summarize() from ...