![]() The main application for the grep function is extracting selected data from a vector or other data set. In this case, we get the names Janet and James because they both start with “Ja” and thereby match our wild card. When the value argument is set to true, the grep function produces a vector of the actual matching values. If the value argument is set to false, the function produces the same result that you get when only using two arguments. In this version of the grep function, we have three arguments with the value argument set to true. In this case, we get two row numbers that are used to produce a data frame consisting of rows containing the two names that start with “Ja.” This approach allows you to extract the entire matching row of a data frame. The result is a vector of the row numbers that match our wild card. In this version of the grep function, we have only two arguments because the value argument is false by default. + Name = c(“Janet”, “Charles”, “Alcaraz”, “James”, “Samantha”, “Bob”), The first one only has two arguments and produces a vector of the row numbers with the match and produces a vector of the matches by adding a third argument. They both use the same basic formula, but they produce different results. Here we have two examples of how-to wildcard match text strings. Using a false value argument works best if you are analyzing a data frame. Using a true value argument works best if you are analyzing a vector. The one you use depends upon the situation. If the vector argument is false, or not included, the function produces a vector consisting of the location of the matching values in the vector being searched. If the value argument is true, it will then create a vector consisting of matching values. The grep function then searches the vector for values that match the wild card. If you want to create a vector consisting of the matching values, then you set the value parameter to true, otherwise, you can just leave it blank. When using the grep function, you put your wild card in the first argument and your vector in the second argument. If the value argument is omitted, it is automatically false. If the value argument is false, then it will provide a vector with the location of each matched data point in the vector argument. If the value argument is true, it will produce a vector containing the matching data. It will provide either the position of the data that fits the wild card or the actual data depending on how the value argument is set. When doing a wild card search in R programming you use the grep function and it has the format of grep(wild card, vector, value). The formula provided by R programming has two output options that have different uses. A wild card is a piece of text that contains common elements that you are looking for. Sometimes when doing data processing you are going to want to pull specific data out of a vector or data frame based on a wild card.
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