pmap | pmap.c : implementation of something like Solaris
kandi X-RAY | pmap Summary
kandi X-RAY | pmap Summary
pmap.c: implementation of something like Solaris' /usr/proc/bin/pmap. Author: Andy Isaacson .
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QUESTION
So I was really ripping my hair out why two different sessions of R with the same data were producing wildly different times to complete the same task.
After a lot of restarting R, cleaning out all my variables, and really running a clean R, I found the issue: the new data structure provided by vroom
and readr
is, for some reason, super sluggish on my script. Of course the easiest thing to solve this is to convert your data into a tibble as soon as you load it in. Or is there some other explanation, like poor coding praxis in my functions that can explain the sluggish behavior? Or, is this a bug with recent updates of these packages? If so and if someone is more experienced with reporting bugs to tidyverse, then here is a repex
showing the behavior cause I feel that this is out of my ballpark.
ANSWER
Answered 2021-Jun-15 at 14:37This is the issue I had in mind. These problems have been known to happen with vroom, rather than with the spec_tbl_df
class, which does not really do much.
vroom
does all sorts of things to try and speed reading up; AFAIK mostly by lazy reading. That's how you get all those different components when comparing the two datasets.
With vroom:
QUESTION
Edited to change the regex and show my tidyr/dplyr
solution
I am looking for an efficient way (preferably purrr
) way to handle a lot searching and counting regex patterns in a large dataframe.
Here is a simple example of what I'm trying to achieve.
Say I have a data frame of sentences:
...ANSWER
Answered 2021-Jun-09 at 14:03You can try using map_df
-
QUESTION
I am trying to compile a tool for my project. I have solved all the problems so far, but i can't find the solution for this problem.
If anyone could give me help, i would appreciate it, Thank you.
NtlScriptEncrypter.cpp
...ANSWER
Answered 2021-Jun-06 at 05:00The solution was: add the project that contains NtlXMLDoc.cpp to my references in explorer of my project, because, they are in the same solution, but are a different project, and idk why through properties didn't worked
QUESTION
I have some data that I am trying to apply a function over. It goes to a URL, collects the JSON data and then stores it into a folder on my computer.
I apply the following code:
...ANSWER
Answered 2021-Jun-04 at 18:12Consider doing this with possibly/safely
QUESTION
I have a bit of code that goes through a number of columns containing dates and selects the earliest date from the options to populate a new column with. To do this I was using the dplyr::rowwise
function.
Unfortunately, the data set is quite big and comes at a time cost in obtaining an output. Here is an example of my initial approach.
...ANSWER
Answered 2021-May-20 at 10:20From my experiance rowwise
is extremely slow so I prefer using any other option (at the cost of having less tidy code) especially if I have numeric columns (then I convert to matrix). pmap
is definitely option, but sometimes I have trouble listing all needed columns (doesn't have tidy select option). This can be somewhat avoided by using select
within pmap
:
QUESTION
I have two lists foo
and bar
, where length(foo) > length(bar)
. I want to apply a function length(bar)
times to each element of bar
and store the output of each application in is own list and store all of the applications of the function to each element of bar
in their own lists. This nested list output structure is important as I am passing it to functions that require nested lists. Examples of what I have and desired are in the minimal example.
While this works nicely with nested for-loops, I've been trying to accomplish this with purrr
's map
functions. I've managed to do this by creating (a) a list of length(bar)
where each element is foo
, (b) passing this new list and bar
to an anonymous function in purrr::pmap()
, and then (c) passing this to an anonymous function in purrr:map()
.
While this works, it seems very antithetical to the purpose of purrr
:
- Instead of
.x
,.y
, and~
syntax, I'm defining anonymous functions. - Instead of passing my raw lists (which vary in length), I'm converting one to a nested list to match the other's length. This can be memory-intensive, slow, etc.
- I'm working with nested lists rather than flatter lists/dataframes I then partition into my desired data structure.
Is there an alternative way of working with different-length lists in purrr
than my aproach? How might I modify my code (minimal example below) to better-exploit the syntax of purrr
? One idea (Handling vectors of different lengths in purrr) is to use cross()
or some equivalent to generate a single object for passing to pmap()
, but I'm not how how to then generate the nested list structure.
ANSWER
Answered 2021-May-15 at 00:21Consider using a nested map
. Loop over the 'bar' list
, then do the loop over the 'foo' and paste
. This will return a nested list
as in the OP's expected
QUESTION
Following on the renaming request #67453183 I want to do the same for formats using the dictionary, because it won't bring together columns of distinct types.
...I have a series of data sets and a dictionary to bring these together. But I'm struggling to figure out how to automate this. > Suppose this data and dictionary (actual one is much longer, thus I want to automate):
ANSWER
Answered 2021-May-10 at 07:11I took another approach than Ronak's to read the dictionary. It is more verbose but I find it a bit more readable. A benchmark would be interesting to see which one is faster ;-)
Unfortunately, it seems that you cannot blindly cast a variable to a factor so I switched to character instead. In practice, it should behave exactly like a factor and you can call as_factor()
on the end object if this is very important to you. Another possibility would be to store a casting function name (such as as_factor()
) in the dictionary, retrieve it using get()
and use it instead of as()
.
QUESTION
I want to generate a dataframe where each row is given by a function of the cross product of several properties. This can be done imperatively:
...ANSWER
Answered 2021-May-06 at 12:30If f
and g
return atomic values to populate dataframe d
, why not just return the complete vectors instead by passing seed
to the functions? E.g.
QUESTION
May be this question termed as part-3 of this question.
I know that arguments in lambda functions when used in tidyverse
especially purrr
functions are written as -
.
when there is only 1 argument.x
&.y
when there are 2- OR
..1
,..2
so on when there are> 2
arguments
In the linked question, I learnt that if all the arguments have to be simultaneously passed we may use ellipsis i.e. ...
.
But my question, why such ...
work only when wrapped inside a c()
and doesn't work when used as such. In the below two syntaxes, second one works while first one doesn't?
ANSWER
Answered 2021-Apr-15 at 11:30The offical documentation has this to be said about the ellipsis:
QUESTION
I have been exploring the various application of using pmap
function and its variations recently and I am particularly interested in using c(...)
to pass all the arguments into. The following data set belongs to another question that we discussed earlier today with a number of very knowledgeable users.
We were supposed to repeat the values in weight
column based on values in Days
column along their respective rows to get the following output:
ANSWER
Answered 2021-Apr-11 at 20:35The issue seems to be mixing the custom anonymous/lambda function (function(Weight, Days, ...)
- where the arguments are named as the same as the column name) with the default lambda function (~
- where the arguments are .x
, .y
if only two elements or if more than two - ..1
, ..2
, ..3
etc). In the OP's code
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