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How to turn on/off ReactJS 'development mode'?
...tely the magic comes down to React embedding references to process.env.NODE_ENV throughout the codebase; these act like a feature toggle.
if (process.env.NODE_ENV !== "production")
// do propType checks
The above is the most common pattern, and other libraries follow it as well. So to "disable" t...
Select random lines from a file
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@J.F.Sebastian The code: sort -R input | head -n <num_lines>. The input file was 279GB, with 2bi+ lines. Can't share it, though. Anyway, the point is you can keep some lines in memory with shuffle to do the random selection of what to output. Sort is going to sort the entire...
How can I replace every occurrence of a String in a file with PowerShell?
...
(Get-Content file.txt) |
Foreach-Object {$_ -replace '\[MYID\]','MyValue'} |
Out-File file.txt
Note the parentheses around (Get-Content file.txt) is required:
Without the parenthesis the content is read, one line at a time, and flows down the pipeline until i...
mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to
...
A query may fail for various reasons in which case both the mysql_* and the mysqli extension will return false from their respective query functions/methods. You need to test for that error condition and handle it accordingly.
mysql_* extension:
NOTE The mysql_ functions are deprecate...
Django templates: verbose version of a choice
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In Django templates you can use the "get_FOO_display()" method, that will return the readable alias for the field, where 'FOO' is the name of the field.
Note: in case the standard FormPreview templates are not using it, then you can always provide your own templat...
How do I size a UITextView to its content?
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I recommend to use CGFLOAT_MAX macro instead of MAXFLOAT. Proper on both of 32/64 bit platforms.
– eonil
Aug 27 '14 at 14:18
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Use 'import module' or 'from module import'?
... * can be particularly useful, if using it as: if(windows):\n\t from module_win import * \n else: \n\t from module_lin import *. Then your parent module can potentially contain OS independent function names, if the function names in module_lin & module_win have same names. It's like conditionall...
How can I have linebreaks in my long LaTeX equations?
...can be precisely controlled. e.g.
\begin{align*}
x&+y+\dots+\dots+x_100000000\\
&+x_100000001+\dots+\dots
\end{align*}
which would line up the first plus signs of each line... but obviously, you can set the alignments wherever you like.
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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...
Remove last character from string. Swift language
...answered Jul 24 '14 at 11:28
gui_dosgui_dos
1,19377 silver badges55 bronze badges
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