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Extracting specific columns from a data frame
...r package, if your data.frame is called df1:
library(dplyr)
df1 %>%
select(A, B, E)
This can also be written without the %>% pipe as:
select(df1, A, B, E)
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Copying data from one SQLite database to another
...rt Into commands for the tables you want to transfer.
INSERT INTO X.TABLE SELECT * FROM Y.TABLE;
Or, if the columns are not matched up in order:
INSERT INTO X.TABLE(fieldname1, fieldname2) SELECT fieldname1, fieldname2 FROM Y.TABLE;
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LINQ query on a DataTable
...w in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;
And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions
AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the...
Convert PEM to PPK file format
...rvers. This function will allow the user to create multiple custom keys by selecting the "My Account/Key Management" option. Once the key has been created the user will be required to select the desired SSH Key during the “Create Server” process for Linux.
Create and Use SSH Keys
Create keys
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Obtain form input fields using jQuery?
...s[field.name] = field.value;
});
Note that this snippet will fail on <select multiple> elements.
It appears that the new HTML 5 form inputs don't work with serializeArray in jQuery version 1.3. This works in version 1.4+
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How do I fix the “You don't have write permissions into the /usr/bin directory” error when installin
I'm trying to install Rails 3 on a brand new MacBook Pro running OS X 10.6.3, Ruby 1.8.7, and Rails 2.3.5 and I'm wondering if I've hosed myself. So far, I've run these commands:
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How do I list all the columns in a table?
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For Oracle (PL/SQL)
SELECT column_name
FROM user_tab_cols
WHERE table_name = 'myTableName'
For MySQL
SHOW COLUMNS FROM table_name
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How to style the with only CSS?
How can I style <option> s of a <select> element with cross-browser compatibility? I know many JavaScript ways which customize the dropdown to convert into <li> , which I'm not asking about.
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SQL Query Where Field DOES NOT Contain $x
...t is meant to be used in subqueries or with predefined lists:
-- subquery
SELECT a FROM x WHERE x.b NOT IN (SELECT b FROM y);
-- predefined list
SELECT a FROM x WHERE x.b NOT IN (1, 2, 3, 6);
If you are searching a string, go for the LIKE operator (but this will be slow):
-- Finds all rows where...
android button selector
This is a button selector such that when normal it appears red, when pressed it appears grey.
6 Answers
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