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Drop data frame columns by name
...multiple variables:
within(df, rm(x, y))
Or if you're dealing with data.tables (per How do you delete a column by name in data.table?):
dt[, x := NULL] # Deletes column x by reference instantly.
dt[, !"x"] # Selects all but x into a new data.table.
or for multiple variables
dt[, c("x","y...
Export from sqlite to csv using shell script
... sqlite3 command options:
sqlite3 -header -csv my_db.db "select * from my_table;" > out.csv
This makes it a one-liner.
Also, you can run a sql script file:
sqlite3 -header -csv my_db.db < my_script.sql > out.csv
Use sqlite3 -help to see the list of available options.
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How can I call a custom Django manage.py command directly from a test driver?
...for a Django manage.py command that does a backend operation on a database table. How would I invoke the management command directly from code?
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How can I get a list of all functions stored in the database of a particular schema in PostgreSQL?
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After some searching, I was able to find the information_schema.routines table and the information_schema.parameters tables. Using those, one can construct a query for this purpose. LEFT JOIN, instead of JOIN, is necessary to retrieve functions without parameters.
SELECT routines.routine_name, pa...
read.csv warning 'EOF within quoted string' prevents complete reading of file
...ng 403 back with read.csv(). Adding quote = "" got me up to 410 rows. read.table() does no better. I wonder what else can be tried...
– Hack-R
Aug 21 '14 at 15:12
2
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UITableView - change section header color
How can I change color of a section header in UITableView?
31 Answers
31
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How to insert element into arrays at specific position?
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@Artefacto "Arrays" in PHP are, in fact, ordered hash tables. PHP arrays act like arrays, but they are never really arrays; nor are they linked lists, or array lists.
– Frederik Krautwald
Aug 10 '14 at 11:31
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Split data frame string column into multiple columns
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5 years later adding the obligatory data.table solution
library(data.table) ## v 1.9.6+
setDT(before)[, paste0("type", 1:2) := tstrsplit(type, "_and_")]
before
# attr type type1 type2
# 1: 1 foo_and_bar foo bar
# 2: 30 foo_and_bar_2 foo ba...
How to do a regular expression replace in MySQL?
I have a table with ~500k rows; varchar(255) UTF8 column filename contains a file name;
13 Answers
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How to scroll to specific item using jQuery?
I have a big table with vertical scroll bar.
I would like to scroll to a specific line in this table using jQuery/Javascript.
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