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How to keep index when using pandas merge
I would like to merge two DataFrames , and keep the index from the first frame as the index on the merged dataset. However, when I do the merge, the resulting DataFrame has integer index. How can I specify that I want to keep the index from the left data frame?
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How important is the order of columns in indexes?
...should put columns that will be the most selective at the beginning of the index declaration. Example:
5 Answers
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Does MySQL index foreign key columns automatically?
Does MySQL index foreign key columns automatically?
9 Answers
9
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Safe (bounds-checked) array lookup in Swift, through optional bindings?
If I have an array in Swift, and try to access an index that is out of bounds, there is an unsurprising runtime error:
19 A...
Indexes of all occurrences of character in a string
...tions without the -1 at the end that Peter Lawrey's solution has had.
int index = word.indexOf(guess);
while (index >= 0) {
System.out.println(index);
index = word.indexOf(guess, index + 1);
}
It can also be done as a for loop:
for (int index = word.indexOf(guess);
index >= 0;...
How to iterate for loop in reverse order in swift?
....
To iterate on a range in reverse order, they can be used as below:
for index in stride(from: 5, to: 1, by: -1) {
print(index)
}
//prints 5, 4, 3, 2
for index in stride(from: 5, through: 1, by: -1) {
print(index)
}
//prints 5, 4, 3, 2, 1
Note that neither of those is a Range member fun...
How many database indexes is too many?
...that occur on the table.
If there's lots of SELECTs and very few changes, index all you like.... these will (potentially) speed the SELECT statements up.
If the table is heavily hit by UPDATEs, INSERTs + DELETEs ... these will be very slow with lots of indexes since they all need to be modified ea...
Check if a value exists in pandas dataframe index
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This should do the trick
'g' in df.index
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Finding index of character in Swift String
... one who couldn't find the solution.
String doesn't implement RandomAccessIndexType. Probably because they enable characters with different byte lengths. That's why we have to use string.characters.count (count or countElements in Swift 1.x) to get the number of characters. That also applies to pos...
Parsing JSON using Json.net
...null) {
char[] charArray = json.ToCharArray();
int index = 0;
object value = ParseValue(charArray, ref index, ref success);
return value;
} else {
return null;
}
}
/// <summary>
/// Converts a Hashtable / ...