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Postgresql GROUP_CONCAT equivalent?
...method, if they are not desired.
Casting ANYARRAY to TEXT best simulates CSV output as elements that contain embedded commas are double-quoted in the output in standard CSV style. Neither array_to_string() or string_agg() (the "group_concat" function added in 9.1) quote strings with embedded comma...
MySQL dump by query
...
You can dump a query as csv like this:
SELECT * from myTable
INTO OUTFILE '/tmp/querydump.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
share
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Filtering Pandas DataFrames on dates
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So when loading the csv data file, we'll need to set the date column as index now as below, in order to filter data based on a range of dates. This was not needed for the now deprecated method: pd.DataFrame.from_csv().
If you just want to show ...
reformat in vim for a nice column layout
I have this dataset in a csv file
13 Answers
13
...
returning in the middle of a using block
...(var textwriter = new StreamWriter(memoryStream))
{
using (var csv = new CsvWriter(textwriter))
{
//..write some stuff to the stream using the CsvWriter
return memoryStream.ToArray();
}
}
}
I was passing in a DataTable to be outputted as csv....
Combine Date and Time columns using python pandas
...ou may have been able to read this in directly e.g. if you were using read_csv using parse_dates=[['Date', 'Time']].
Assuming these are just strings you could simply add them together (with a space), allowing you to apply to_datetime:
In [11]: df['Date'] + ' ' + df['Time']
Out[11]:
0 01-06-2013...
Sorting multiple keys with Unix sort
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Here is one to sort various columns in a csv file by numeric and dictionary order, columns 5 and after as dictionary order
~/test>sort -t, -k1,1n -k2,2n -k3,3d -k4,4n -k5d sort.csv
1,10,b,22,Ga
2,2,b,20,F
2,2,b,22,Ga
2,2,c,19,Ga
2,2,c,19,Gb,hi
2,2,c,19,Gb,hj
2,...
Pandas every nth row
...came up with when using the index was not viable ( possibly the multi-Gig .csv was too large, or I missed some technique that would allow me to reindex without crashing ).
Walk through one row at a time and add the nth row to a new dataframe.
import pandas as pd
from csv import DictReader
def make_...
内存管理内幕：动态分配的选择、折衷和实现 - C/C++ - 清泛网 - 专注C/C++及内核技术
...地址映射到物理的 RAM 或者 swap，它还可以将 它们映射到文件和文件位置，这样，读写内存将对文件中的数据进行读写。不过，在这里，我们只关心 mmap 向进程添加被映射的内存的能力。 munmap() 所做的事情与 mmap() 相反。
如您...
How is mime type of an uploaded file determined by browser?
...70 (kPrimaryMappings and kSecondaryMappings).
An example: when uploading a CSV file from a Windows system with Microsoft Excel installed, Chrome will report this as application/vnd.ms-excel. This is because .csv is not specified in the first hard-coded list, so the browser falls back to the system r...