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Filter dataframe rows if value in column is in a set list of values [duplicate]
...e a list of exact matches, but if you have a list of partial matches or substrings to look for, you can filter using the str.contains method and regular expressions.
For example, if we want to return a DataFrame where all of the stock IDs which begin with '600' and then are followed by any three di...
Postgresql SELECT if string contains
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A proper way to search for a substring is to use position function instead of like expression, which requires escaping %, _ and an escape character (\ by default):
SELECT id FROM TAG_TABLE WHERE position(tag_name in 'aaaaaaaaaaa')>0;
...
Difference between Covariance & Contra-variance
...rable<out T>, Func<out T>
You can convert from IEnumerable<string> to IEnumerable<object>, or Func<string> to Func<object>. Values only come out from these objects.
It works because if you're only taking values out of the API, and it's going to return something ...
How does the HyperLogLog algorithm work?
...n be of different sizes. One element can be 1 another element "is this big string". So if you have a huge list (or a huge stream of elements) it will take a lot memory.
Probabilistic Counting
How can one get a reasonable estimate of a number of unique elements? Assume that you have a string of l...
How to detect idle time in JavaScript elegantly?
...the end of an expression statement are optional and you can in fact pass a string to setInterval, which then gets evaluated as JavaScript.
– Felix Kling
Nov 17 '13 at 17:51
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Call one constructor from another
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Like this:
public Sample(string str) : this(int.Parse(str)) { }
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What is the result of % in Python?
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Somewhat off topic, the % is also used in string formatting operations like %= to substitute values into a string:
>>> x = 'abc_%(key)s_'
>>> x %= {'key':'value'}
>>> x
'abc_value_'
Again, off topic, but it seems to be a little document...
Reading InputStream as UTF-8
...a 7 it is possible to write the provide the Charset as a Constant not as a String StandardCharsets.UTF_8
– tobijdc
Apr 16 '15 at 9:14
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Why use 'virtual' for class properties in Entity Framework model definitions?
...lized behavior if they implement get and set accessors.
public virtual string Name { get; set; }
// ordinary virtual property with backing field
private int num;
public virtual int Number
{
get { return num; }
set { num = value; }
}
}
class MyDerivedClass :...
Escaping keyword-like column names in Postgres
...ml#delimited%20identifier
This is the code to quote the identifier:
static String delimited_identifier (String identifier)
{
return "\"" + identifier.replaceAll ("\"", "\"\"") + "\"";
}
And this is the code to build the insert:
static String build_insert (String table, String[] columns)
{
Strin...