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R Programming Articles
Page 67 of 174
How to add a column in an R data frame with consecutive numbers?
Addition of a column with consecutive might have different objectives such as getting the sequence of numbers, representing serial numbers, representing ids, identification of each row, or a variable. We can use the sequence starting from any number up to the number of rows if we know the number of rows for this purpose.Example1Consider the below data frame:> x1 x2 df1 df1Output x1 x2 1 6.137898 5.203712 2 5.283467 5.057344 3 5.873749 4.907388 4 7.628762 5.012650 5 4.134700 4.988379 6 5.340686 4.684900 7 5.126999 4.821752 8 3.722762 4.974044 9 4.097969 ...
Read MoreHow to find the residual of a glm model in R?
In a linear model, a residual is the difference between the observed value and the fitted value and it is not different for a general linear model. The difference between linear model and the general linear model is that we use a probability distribution to create a general linear model. If we want to find the residual for a general linear model then resid function can be used just like it is used with the linear model.Example1Consider the below data frame:> x1 y1 df1 df1Output x1 y1 1 4 2 2 3 3 3 5 3 4 4 2 5 ...
Read MoreHow to find the mean of row values in an R data frame using dplyr?
The mean of row values can be found by using rowwise function of dplyr package along with the mutate function to add the new column of means in the data frame. The rowwise function actually helps R to read the values in the data frame rowwise and then we can use mean function to find the means as shown in the below examples.Example1Consider the below data frame:> x1 x2 df1 df1Output x1 x2 1 0 8 2 2 3 3 2 5 4 0 5 5 3 2 6 0 10 7 3 5 8 1 7 9 0 4 ...
Read MoreHow to find the correlation coefficient between two data frames in R?
If two data frames in R have equal number of columns then we can find the correlation coefficient among the columns of these data frames which will be the correlation matrix. For example, if we have a data frame df1 that contains column x and y and another data frame df2 that contains column a and b then the correlation coefficient between df1 and df2 can be found by cor(df1, df2).Example1Consider the below data frame:> x1 x2 df1 df1Output x1 x2 1 39.56630 38.25632 2 39.43689 44.14647 3 40.80479 37.43309 4 ...
Read MoreHow to convert a named vector to a list in R?
A named vector cannot be directly converted to a list because we would need to un-name the vector names and convert those names to names of the list elements. This can be done by using lapply function function. For example, suppose we have a named vector x then it can be converted to a list by using the command x x1 names(x1) x1OutputA B C D E F G H I J K L M N O P Q R S T U V W X Y Z 1 2 3 4 5 6 7 8 9 10 11 12 ...
Read MoreHow to create a sequence of dates by using starting date in R?
The best way to create a sequence of anything is creating it with the help of seq function and this also applies to sequences of dates. But in case of dates, we need to read the dates in date format so that R can understand the input type and create the appropriate vector. If we do not use the date format for the date value then it won’t make sense to R and it will result in error.Examplesx1
Read MoreHow to find different elements between two string vectors in R?
Just like numerical vectors, we can find the different elements between two string vectors if there exists any. For this purpose, we can use setdiff function. For example, if we have a vector V1 that contains a, b, c, d, e, f and the other vector V2 that contains a, e, h, k, l, p, r, u, v, w then the different elements between these two vectors can be found as setdiff(V1,V2).Examplex1
Read MoreHow to find the sum of corresponding elements in multiple vectors even if they contain NA’s in R?
If we have multiple vectors then the sum of the corresponding elements can be found by using rowSums functions and the vectors can be combined by using cbind so that R can easily read the corresponding elements. But if there are NA values in one or more vectors then we also need to add na.rm=TRUE argument.Exampleset.seed(100) x1
Read MoreHow to find the difference between regression line and the points in R?
The difference between regression line and the points on the scatterplot are actually the residuals, thus we need to calculate the residual from the model object. This can be simply done by using residuals function. For example, if we create a linear model defined as Model between x and y then the residuals will be found as residuals(Model).Consider the below data frame −Exampleset.seed(999) x1
Read MoreHow to find the index of the last occurrence of repeated values in a vector in R?
Indexing helps us to understand the location of the value in the vector. If we have a vector that contains repeated values then we might want to figure out the last occurrence of the repeated value. For example, if we have a vector x that contains 1, 1, 2, 1, 2 then the last occurrence of repeated values will be 4 and 5 because the last 1 is at 4th position and 2 is at the 5th position. We can find this by using tapply function in R.Examplex1
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