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How to rollback a specific migration?
...nt to go back.
For example:
rake db:rollback STEP=5
Will also rollback all the migration that happened later (4, 3, 2 and also 1).
To roll back all migrations back to (and including) a target migration, use: (This corrected command was added AFTER all the comments pointing out the error in the ...
How do I use vim registers?
...on Windows (or from "mouse highlight" clipboard on Linux)
"*p
To access all currently defined registers type
:reg
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Sorting Python list based on the length of the string
...
def lensort(list_1):
list_2=[];list_3=[]
for i in list_1:
list_2.append([i,len(i)])
list_2.sort(key = lambda x : x[1])
for i in list_2:
list_3.append(i[0])
return list_3
This works for me!
...
How do I run a Ruby file in a Rails environment?
...------
#!/usr/bin/env /Users/me/rails_project/script/rails runner
Product.all.each { |p| p.price *= 2 ; p.save! }
-------------------------------------------------------------
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adding noise to a signal in python
...umpy as np
import matplotlib.pyplot as plt
t = np.linspace(1, 100, 1000)
x_volts = 10*np.sin(t/(2*np.pi))
plt.subplot(3,1,1)
plt.plot(t, x_volts)
plt.title('Signal')
plt.ylabel('Voltage (V)')
plt.xlabel('Time (s)')
plt.show()
x_watts = x_volts ** 2
plt.subplot(3,1,2)
plt.plot(t, x_watts)
plt.title...
What is memoization and how can I use it in Python?
...orials using memoization in Python would be something like this:
factorial_memo = {}
def factorial(k):
if k < 2: return 1
if k not in factorial_memo:
factorial_memo[k] = k * factorial(k-1)
return factorial_memo[k]
You can get more complicated and encapsulate the memoization...
Backbone.View “el” confusion
...
A views el is where all the event binding takes place. You don't have to use it but if you want backbone to fire events you need to do your rendering work on the el. A views el is a DOM element but it does not have to be a pre-existing element. ...
MySQL query to get column names?
I'd like to get all of a mysql table's col names into an array in php?
21 Answers
21
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How to replace captured groups only?
...ding and following text:
str.replace(/(.*name="\w+)(\d+)(\w+".*)/, "$1!NEW_ID!$3")
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Adjust UILabel height to text
...ne about some println's or just a line with only comments (then it says EXC_BAD_ACCESS code=2 as well)
– TheBurgerShot
Aug 8 '14 at 11:52
6
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