Oh, shoot! Most groups have missing values in them, so we get NA back. We need to use na.rm = TRUEjust like before. Thankfully, it is possible to pass this option to mean() inside aggregate() as well:
data(starwars) loads the example dataset called starwars that is included in the packagedplyr. As I said earlier, this is just an example; you could have loaded an external dataset,from a .csv file for instance. This does not matter for what comes next.
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You might have noticed that because there is no data for the years 2016 and 2017, these columns donot appear in the data. But suppose that we need to have these columns, so that a colleague fromanother department can fill in the values. This is possible by providing a data frame with thedetailed specifications of the result data frame. This optional data frame must have at least twocolumns, .name, which are the column names you want, and .value which contains the values.Also, the function that uses this spec is a pivot_wider_spec(), and not pivot_wider().
factor variables have different levels and the forcats package includes functions that allowyou to recode, collapse and do all sorts of things on these levels. For example , usingforcats::fct_recode() you can recode levels:
lubridate is yet another tidyverse package, that makes dealing with dates or durations (and intervals) aspainless as possible. I do not use every function contained in the package daily, and as such willonly focus on some of the functions. However, if you have to deal with dates often,you might want to explore the package thouroughly.
Even though the file is an XML file, I still read it in using read_lines() and not read_xml()from the xml2 package. This is for the purposes of the current exercise, and also because Ialways have trouble with XML files, and prefer to treat them as simple text files, and use regularexpressions to get what I need.
This returns a boolean atomic vector of the same length as winchester. If the string CONTENT isnowhere to be found, the result will equal FALSE, if not it will equal TRUE. Here it is easy tosee that the last element contains the string CONTENT. But what if instead of having 43 elements,the vector had 24192 elements? And hundreds would contain the string CONTENT? It would be easierto instead have the indices of the vector where one can find the word CONTENT. This is possiblewith str_which():
You can interpret the result as follows: in the rows, the index of the vector where thestring us is found. So the 3rd, 5th and 6th philosopher have us somewhere in their name.The result also has two columns: start and end. These give the position of the string. So thestring us can be found starting at position 8 of the 3rd element of the vector, and ends at position9. Same goes for the other philisophers. However, consider Marcus Aurelius. He has two names, bothending with us. However, str_locate() only shows the position of the us in Marcus.
The tidyverse collection of packages can do much more than simply data manipulation anddescriptive statisics. You can use the principles we have covered and the functions you now knowto do much more. For instance, you can use a few tidyverse functions to do Monte Carlo simulations,for example to estimate \(\pi\).
Draw the unit circle inside the unit square, the ratio of the area of the circle to the area of thesquare will be \(\pi/4\). Then shot K arrows at the square; roughly \(K*\pi/4\) should have falleninside the circle. So if now you shoot N arrows at the square, and M fall inside the circle, you havethe following relationship \(M = N*\pi/4\). You can thus compute \(\pi\) like so: \(\pi = 4*M/N\).
Using a data frame as a structure to hold our simulated points and the results makes it very easyto avoid loops, and thus write code that is more concise and easier to follow.If you studied a quantitative field in university, you might have done a similar exercise at thetime, very likely by defining a matrix to hold your points, and an empty vector to hold whether aparticular point was inside the unit circle. Then you wrote a loop to compute whethera point was inside the unit circle, save this result in the before-defined empty vector and thencompute the estimation of \(\pi\). Again, I take this opportunity here to stress that there is nothingwrong with this approach per se, but R is better suited for a workflow where lists or data framesare the central objects and where the analyst operates over them with functional programming techniques.
You can also create SparkDataFrames from Hive tables. To do this we will need to create a SparkSession with Hive support which can access tables in the Hive MetaStore. Note that Spark should have been built with Hive support and more details can be found in the SQL Programming Guide. In SparkR, by default it will attempt to create a SparkSession with Hive support enabled (enableHiveSupport = TRUE).
Formally, the group mentioned above is called the frame. Every input row can have a unique frame associated with it and the output of the window function on that row is based on the rows confined in that frame.
dapply can apply a function to each partition of a SparkDataFrame. The function to be applied to each partition of the SparkDataFrame should have only one parameter, a data.frame corresponding to a partition, and the output should be a data.frame as well. Schema specifies the row format of the resulting a SparkDataFrame. It must match to data types of returned value. See here for mapping between R and Spark.
We can easily split SparkDataFrame into random training and test sets by the randomSplit function. It returns a list of split SparkDataFrames with provided weights. We use carsDF as an example and want to have about \(70%\) training data and \(30%\) test data.
Most of the common operations on SparkDataFrame are supported for streaming, including selection, projection, and aggregation. Once you have defined the final result, to start the streaming computation, you will call the write.stream method setting a sink and outputMode.
The main method calls of actual computation happen in the Spark JVM of the driver. We have a socket-based SparkR API that allows us to invoke functions on the JVM from R. We use a SparkR JVM backend that listens on a Netty-based socket server.
If you have an infection, you should not donate blood and plasma. When taking medication for an infection, you may temporarily be unable to donate. Learn more about medications below. For additional information, please call to speak with one of our trained health professionals at 1 888 2 DONATE (1 888 236-6283).
There is no deferral for cocaine use, except if used intravenously. If you have ever used cocaine intravenously, you are not eligible to donate. At the time of donation, donors must not be intoxicated as this prevents us from obtaining informed consent for blood donation.
You may be eligible to donate if you have been seizure-free for six (6) months. If you are taking medication to manage epilepsy, please consult our list of medications below or call to speak with one of our trained health professionals at 1 888 2 DONATE (1 888 236-6283) to discuss your eligibility.
If you have received a false positive result in the past and would like to set up an appointment to be re-tested, please call 1 888 2 DONATE (1 888 236-6283) to speak with one of our trained health professionals.
For instance, donors who have travelled to locations outside of Canada, the continental U.S. and Europe have a waiting period of 21 days after their return home before donating blood or plasma. These new criteria were introduced in February 2016, to identify donors at greater risk for acquiring illnesses spread by mosquitos such as Zika virus.
Because the risk of infection diminishes over time, people who have lived for six (6) months or longer in a country where malaria is prevalent are deferred for blood donation for three (3) years after departure from the country, but they can donate plasma.
Those who have visited a malaria risk area are deferred from blood donation for three (3) months after leaving that area, but they can donate plasma. If your visit lasted less than 24 hours, please call us at 1 888 2 DONATE (1 888 236-6283) to discuss your eligibility.
Individuals who have developed iron accumulation causing organ compromise are not eligible to donate whole blood at a Canadian Blood Services donor centre. Therapeutic phlebotomies can be arranged through the treating health care practitioner under medical supervision. Once organ function improves, individuals with hemochromatosis can become eligible to donate whole blood.
To ensure donors have sufficient blood levels after donation and to prevent anemia, a minimum hemoglobin level is required at each donation. This required hemoglobin level is slightly higher than the level that is used to diagnose anemia.
Hemoglobin level is tested using a fingerpick test before each donation. For whole blood, platelets and some types of plasma donation, donors registered as male must have a hemoglobin level of at least 130 g/L and donors registered as females must have a hemoglobin level of at least 125 g/L.
If you live with or have had sexual contact with a person who has or had hepatitis, call us to speak with one of our trained professionals at 1 888 2 DONATE (1 888 236-6283) to discuss your eligibility.
People who have had malaria in the past are not eligible to donate whole blood or platelets. Malaria is a blood borne illness, which is why our eligibility criteria are so strict. The parasite that causes malaria can lie dormant long after someone has recovered from the disease. This means that no matter how much time has passed, there remains a small but significant risk that someone who has had malaria at some point in their lives may still carry the malarial parasite in their red blood cells and platelets.
However, you may be able to donate plasma if it has been six (6) months or more since you have recovered from malaria. This is because the process used to manufacture medications from plasma removes the parasite that causes malaria. 2ff7e9595c
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