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Only read selected columns
...from the data.table-package:
You can specify the desired columns with the select parameter from fread from the data.table package. You can specify the columns with a vector of column names or column numbers.
For the example dataset:
library(data.table)
dat <- fread("data.txt", select = c("Year...
select、poll、epoll之间的区别总结[整理] - C/C++ - 清泛网 - 专注C/C++及内核技术
select、poll、epoll之间的区别总结[整理]select，poll，epoll都是IO多路复用的机制。I O多路复用就通过一种机制，可以监视多个描述符，一旦某个描述符就绪（一般是读就绪或者写就绪...select，poll，epoll都是IO多路复用的机制。I/O多路...
Check if a value exists in pandas dataframe index
...ues or the index by appending the ".values" method, e.g.
g in df.<your selected field>.values
g in df.index.values
I find that adding the ".values" to get a simple list or ndarray out makes exist or "in" checks run more smoothly with the other python tools. Just thought I'd toss that out th...
Creating a div element in jQuery [duplicate]
... @halfer vice versa then, use single quotes in javascript for selectors and any appended html with double quotes.
– Ricki
Oct 22 '11 at 18:04
72
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PHP code to convert a MySQL query to CSV [closed]
...
SELECT * INTO OUTFILE "c:/mydata.csv"
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
LINES TERMINATED BY "\n"
FROM my_table;
(the documentation for this is here: http://dev.mysql.com/doc/refman/5.0/en/select.html)
or:...
Find value in an array
...
Using Array#select will give you an array of elements that meet the criteria. But if you're looking for a way of getting the element out of the array that meets your criteria, Enumerable#detect would be a better way to go:
array = [1,2,...
ssh “permissions are too open” error
...ress Add... then type your name in the text box "Enter the object names to select" then press Check Names button (and press OK and another OK) then your name should be listed in the Security tab
– Supawat Pusavanno
Oct 16 '19 at 19:23
...
Is there an Eclipse line-width marker?
...ou have to set it in the formatter: From menu [Window]-->[Preferences], select [Java]-->[Code Style]-->[Formatter], and then edit your formatter profile. In the tab page [Line wrapping], you can find a setting named "Maximum line width". Change this setting, and the print margin in Java sou...
get list of pandas dataframe columns based on data type
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If you are just selecting columns by data type, then this answer is obsolete. Use select_dtypes instead
– Ted Petrou
Nov 3 '17 at 16:58
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How to access pandas groupby dataframe by key
...t uses data-structures already available in the groupby object.
You can select different columns using the groupby slicing:
In [22]: gb[["A", "B"]].get_group("foo")
Out[22]:
A B
0 foo 1.624345
2 foo -0.528172
4 foo 0.865408
In [23]: gb["C"].get_group("foo")
Out[23]:
0 5
2 ...