Do you need more explanations? Before we can dive into the transformation of a character variable to numeric, we need to create an example character in R.
Consider the following vector:. Now, we can continue with the important part — How to convert this character string to numeric? However, if you need some more explanations for the conversion of data types, you might have a look at the following video of my YouTube channel. As you have seen, to convert a vector or variable with the character class to numeric is no problem. However, sometimes it makes sense to change all character columns of a data frame or matrix to numeric. With the following R code, you are able to recode all variables — no matter which variable class — of a data frame to numeric:.
However, in many situations it is better to convert only character columns to numeric i. You could do that with the following code in R:. Further examples needed? The speaker discusses different data transformations from one data class to another. Your email address will not be published. Post Comment. Subscribe to my free statistics newsletter. Leave a Reply Cancel reply Your email address will not be published.
We see that x must be a matrix of the predictors, y must be a matrix with the dependent usually just onethe weights and alpha are optional, but since I am working with aggregate data I am almost always using weights. Alpha controls the kind of shrinkage used. In my case, the predictor data. R actually uses numeric values as its internal representation of these, but displays them with strings. For instance:. However, suppose we use my as.
Which is not what we wanted. It gave us a character matrix which glmnet. Their bad error made me spend some time finding the actual error. Save yourself and others time. Always write good error messages for functions that will be used more than a couple of times! However, it does work for a single column.
So maybe we can just try using it on all the columns:. It looks apply does a silent as. How do we convert just the factor columns then? Maybe try some of the more fancy built in conversion calls:.
Closer, this time the date got converted, but the factor got converted to character, not integers. We could do a loop:. Which works, but now it is getting silly. Maybe some implicit loops:. Closer, but it returns a list, not a matrix. Maybe just try converting:. What about as. Huh, that works, but as. Oh well, just one final step:.
Original post Sometimes you need to use a function that wants a numeric matrix as input. Is there some easy built in way to solve the problem? What is going on? Sometimes, R does not make your life easy.This function converts replaces factor levels with the related factor level index number, thus the factor is converted to a numeric variable. S3 method for data. Optional, unquoted names of variables that should be selected for further processing.
Required, if x is a data frame and no vector and only selected variables from x should be processed. See 'Examples'. Starting index, i. By default, this argument is NULLhence the lowest value of the returned numeric variable corresponds to the lowest factor level if factor levels are numeric or to 1 if factor levels are not numeric. Logical, if TRUEformer factor levels will be added as value labels.
For numeric factor levels, values labels will be used, if present. A numeric variable with values ranging either from start. If x is a data frame, the complete data frame x will be returned, where variables specified in Created by DataCamp. Convert factors to numeric variables This function converts replaces factor levels with the related factor level index number, thus the factor is converted to a numeric variable.
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I know that I need to use as. I tried to apply it to the entire data.
If the columns are factor class, convert to character and then to numeric. Also, note that if there are no character elements in any of the cells, then use type. Convert a Data Frame to a Numeric Matrix. Learn more.
How to convert an entire data. Asked 1 year, 5 months ago. Active 1 year, 5 months ago. Viewed 5k times. I want to convert an entire data. Stedy 6, 14 14 gold badges 50 50 silver badges 71 71 bronze badges. MoMo MoMo 93 2 2 silver badges 8 8 bronze badges.
Active Oldest Votes. If efficiency matters, one option is data. I routinely use as.Pandas Tutorial - How to convert a dataframe to a list
I am aware of the levels route.Return the matrix obtained by converting all the variables in a data frame to numeric mode and then binding them together as the columns of a matrix.
Factors and ordered factors are replaced by their internal codes. Logical and factor columns are converted to integers. Any other column which is not numeric according to is. If all columns are integer after conversion the result is an integer matrix, otherwise a numeric double matrix. If frame inherits from class "data. Chambers, J. Chapter 3 of Statistical Models in S eds J. Chambers and T. For more information on customizing the embed code, read Embedding Snippets.
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data.matrix: Convert a Data Frame to a Numeric Matrix
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I have a mixed class dataframe numeric and factor where I am trying to convert the entire data frame to numeric. The following illustrates the type of data I am working with as well as the problem I am encountering:.
When I try and convert the entire data frame to numeric, it alters the numeric values. For example:. Previous posts on this site suggest using as. However, I need to apply this approach to a dataframe that may contain hundreds of columns. What are my options for converting an entire dataframe from factor to numeric, while preserving the numeric decimal values? The following is the output I would like to produce where a and b are numeric:. You might need to do some checking. You cannot safely convert factors directly to numeric.
Otherwise, the factors will be converted to their numeric storage values. I would check each column with is. Learn more. How to convert entire dataframe to numeric while preserving decimals? Ask Question.
Converting a data.frame to a numerical matrix in R, not so easy!
Asked 5 years, 5 months ago. Active 1 year, 5 months ago. Viewed 77k times. The following is the output I would like to produce where a and b are numeric: a b 1 0. This post does not take into account decimal values. How can i convert a factor column that contains decimal numbers to numeric? This applies to only one column in a data frame. Borealis Borealis 5, 12 12 gold badges 51 51 silver badges 96 96 bronze badges.
Great way to ask a question. This question may be helpful.
How to Convert a Character to Numeric in R
This is a common source of frustration with factor variables. Active Oldest Votes. Rich Scriven Rich Scriven It is more efficient to check first, and then run the change on the subset? Rather than checking inside the lapply loop?
Using dplyr a bit like sapply. Prost R.No matter if you need to change the class of factors, characters, or integersthis tutorial will show you how to do it. First we need to create some data in R that we can use in the examples later on:. You can see the structure of our example data frame in Table 1.
The data contains three columns: a factor variablea character variableand an integer variable. For this task, we can use the following R code:.
Note: The previous code converts our factor variable to character first and then it converts the character to numeric. This is important in order to retain the values i. You can learn more about that in this tutorial. If you need more explanation on the R syntax of Example 1, you might have a look at the following YouTube video.
In Example 1 we used the as. However, when we want to change several variables to numeric simultaneously, the approach of Example 1 might be too slow i. First, we need to specify which columns we want to modify. In this example, we are converting columns 2 and 3 i. Converting variable classes in R is a complex topic. I have therefore listed some additional resources about the Modification of R data classes in the following. If you want to learn more about the basic data types in R, I can recommend the following video of the Data Camp YouTube channel:.
I hope you liked this tutorial! Let me know in the comments if you have any further questions and of cause I am also happy about general feedback. Your email address will not be published.
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