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Ruby on Rails - Import Data from a CSV file
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The smarter_csv gem was specifically created for this use-case: to read data from CSV file and quickly create database entries.
require 'smarter_csv'
options = {}
SmarterCSV.process('input_file.csv', options) do |chunk|
chunk.each do |data_hash|
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Where to define custom error types in Ruby and/or Rails?
... error types in a Ruby library (gem) or Ruby on Rails application? Specifically:
5 Answers
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Selecting a row of pandas series/dataframe by integer index
... edited Jun 5 '18 at 12:40
marc_aragones
3,37644 gold badges2323 silver badges3333 bronze badges
answered Apr 19 '13 at 12:20
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How do I make a textbox that only accepts numbers?
... with this two event handlers on a standard TextBox:
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&
(e.KeyChar != '.'))
{
e.Handled = true;
}
// only allow one de...
What is a bus error?
... when your processor cannot even attempt the memory access requested, typically:
using a processor instruction with an address that does not satisfy its alignment requirements.
Segmentation faults occur when accessing memory which does not belong to your process, they are very common and are typ...
How do you create different variable names while in a loop? [duplicate]
...can do this is with exec(). For example:
for k in range(5):
exec(f'cat_{k} = k*2')
>>> print(cat_0)
0
>>> print(cat_1)
2
>>> print(cat_2)
4
>>> print(cat_3)
6
>>> print(cat_4)
8
Here I am taking advantage of the handy f string formatting in Pytho...
What are 'closures' in .NET?
...thod and the variable j
[CompilerGenerated]
private sealed class <>c__DisplayClass2
{
public <>c__DisplayClass2();
public void <fillFunc>b__0()
{
Console.Write("{0} ", this.j);
}
public int j;
}
for the function:
static void fillFunc(int count) {
...
How to overcome TypeError: unhashable type: 'list'
...used to compare dictionary keys during a dictionary lookup quickly.
Internally, hash() method calls __hash__() method of an object which are set by default for any object.
Converting a nested list to a set
>>> a = [1,2,3,4,[5,6,7],8,9]
>>> set(a)
Traceback (most recent call last...
Functional programming - is immutability expensive? [closed]
...’d like to clarify some points.
The “in-place” quicksort isn’t really in-place (and quicksort is not by definition in-place). It requires additional storage in the form of stack space for the recursive step, which is in the order of O(log n) in the best case, but O(n) in the worst case.
Im...
Should I use the datetime or timestamp data type in MySQL?
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Timestamps in MySQL are generally used to track changes to records, and are often updated every time the record is changed. If you want to store a specific value you should use a datetime field.
If you meant that you want to decide between using a UNIX ...