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Determine the number of NA values in a column
...nt the number of NA values in a data frame column. Say my data frame is called df , and the name of the column I am considering is col . The way I have come up with is following:
...
Difference between std::system_clock and std::steady_clock?
...11.7.1 [time.clock.system]/1:
Objects of class system_clock represent wall clock time from the system-wide realtime clock.
20.11.7.2 [time.clock.steady]/1:
Objects of class steady_clock represent clocks for which values of time_point never decrease as physical time advances and for which v...
UnmodifiableMap (Java Collections) vs ImmutableMap (Google) [duplicate]
...// Will return "F".
In contrast to that, the ImmutableMap of Guava is really immutable: It is a true copy of a given map, and nobody may modify this ImmutableMap in any way.
Update:
As pointed out in a comment, an immutable map can also be created with the standard API using
Map<String, S...
Relative frequencies / proportions with dplyr
...
Try this:
mtcars %>%
group_by(am, gear) %>%
summarise(n = n()) %>%
mutate(freq = n / sum(n))
# am gear n freq
# 1 0 3 15 0.7894737
# 2 0 4 4 0.2105263
# 3 1 4 8 0.6153846
# 4 1 5 5 0.3846154
From the dplyr vigne...
invalid byte sequence for encoding “UTF8”
... the iconv utility to change encoding of the input data.
iconv -f original_charset -t utf-8 originalfile > newfile
You can change psql (the client) encoding following the instructions on Character Set Support. On that page, search for the phrase "To enable automatic character set conversion".
...
Referencing a string in a string array resource with xml
...eferencing an XML string in an XML Array (Android)
You can "cheat" (not really) the array definition by addressing independent strings INSIDE the definition of the array. For example, in your strings.xml:
<string name="earth">Earth</string>
<string name="moon">Moon</string>...
What are Scala context and view bounds?
...rds, A should have an implicit conversion to B available, so that one can call B methods on an object of type A. The most common usage of view bounds in the standard library (before Scala 2.8.0, anyway), is with Ordered, like this:
def f[A <% Ordered[A]](a: A, b: A) = if (a < b) a else b
Be...
How to change package name of an Android Application
...ould try these instructions from Android's developer site. They're specifically for the GestureBuilder sample but should apply to any application as far as I can tell:
[H]ere's how you could do this in Eclipse:
Right-click on the package name (src/com.android.gesture.builder).
Select R...
Should I pass a shared_ptr by reference? [duplicate]
...mber of bugs arise from improper lifetime management. What's worse conceptually is that it is never clear who owns the objects whose pointers the container stores. The pointers could even be a mix of pointers to dynamic objects, automatic objects, and garbage. Nobody can tell. So the standard soluti...
How to customize ?
...seinput">El Cucaratcha, for example</button>
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