I had a very big list of data in R, and I used the following line:
subsetList <- tmpList[tmpList$colName=="value"]
Where colName is the name of the column in the list and 'value' is the text I wanted to subset 'tmpList' on.
The result was I received was a complete replication of 'tmpList' in the new list.
After some experimenting, I used the following instead:
subsetList <- tmpList[tmpList$colName=="value" , ]
(Note the comma inserted.)
Now my 'subsetList' contains only the rows where the content of the column given by 'colName' is matching to "value".
Why does the first attempt return all the rows? And why does the second attempt return only rows matching the equivalence criteria?
Related
I have a dataframe with over 100 columns. Post implementation of certain conditions, I need a subset of the dataframe with the columns that are listed in a separate array.
The array has 50 entries with 2 columns. The first column has the selected variable names and the second column has some associated values.
I wish to build a new data frame with just the variables mentioned in the the first column of the separate array. Could you please point me as to how to proceed?
Try this:
library(dplyr)
iris <- iris %>% select(contains(dataframe_with_names$names))
In R you can use square brackets [rows, columns] to select specific rows or specific columns. (Leaving either blank selects all).
If you had a vector of column names you wanted to keep called important_columns you could select only those columns with:
myData[,important_columns]
In your case the vector of column names is actually a column in your array. So you select that column and use it as your vector:
myData[, array$names]
Working in RStudio, I am performing an api to openweathermap.
The json returned is converted to a dataframe.
The code that I am using to get the JSON is:
text2 <- GET('https://api.openweathermap.org/data/2.5/onecall/timemachine?lat=43.15&lon=-89.29&dt=1621425600&appid=yourappidhere')
jsonOpenWeather <- fromJSON(rawToChar(text2$content))
The returned column jsonOpenWeather$weather is the column containing lists. Each list has four variables ('id', 'main', 'description', 'icon') and oberservations ranging from 1 to 4.
I would like to extract the first observation from the second variable and have this value replace its originating list.
We can use sapply to loop over the 'weather' column of the object, extract the main column and get the first observation
jsonOpenWeather2 <- sapply(jsonOpenWeather$weather, function(x) x$main[1])
I have a dataframe with multiple columns that I want to group according to their names. When several columns names respond to the same pattern, I want them grouped in a single column and that column is the sum of the group.
colnames(dataframe)
[1] "Départements" "01...3" "01...4" "01...5" "02...6" "02...7" "02...8" "02...9" "02...10" "03...11"
[11] "03...12" "03...13" "04...14" "04...15" "05...16" "05...17" "05...18" "06...19" "06...20" "06...21"
So I use this bit of code that works just fine when every column are numeric, though the first one is character and therefore I hit an error. How can I exclude the first column from the code?
#Group columns by patern, look for a pattern and loop through
patterns <- unique(substr(names(dataframe_2012), 1, 3))` #store patterns in a vector
dataframe <- sapply(patterns, function(xx) rowSums(dataframe[,grep(xx, names(dataframe)), drop=FALSE]))
#loop through
This is the error code I get
Error in rowSums(DEPTpolicedata_2012[, grep(xx, names(DEPTpolicedata_2012)), :
'x' must be numeric
You can simply remove the first column using
patterns$Départements <- NULL
I have a Seurat R object. I would like to only select the data corresponding to a specific sample. Therefore, I want to get only the row names that contain a specific character. Example of my differences in row names: CTAAGCTT-1 and CGTAAAT-2. I want to differentiate based on 1 and 2. The code below shows what I already tried. But it just returns the total numbers of row. Not how many rows are matching the character.
length <- length(rownames(seuratObject#meta.data) %in% "1")
OR
length <- length(grepl("-1",rownames(seuratObj#meta.data)))
Idents(seuratObject, cells = 1:length)
Thanks for any input.
Just missing which()
length(which(grepl("-1", rownames(seuratObject#meta.data))))
I would like to assign names to rows in R but so far I have only found ways to assign names to columns. My data is in two columns where the first column (geo) is assigned with the name of the specific location I'm investigating and the second column (skada) is the observed value at that specific location. To clarify, I want to be able to assign names for every location instead of just having them all in one .txt file so that the data is easier to work with. Anyone with more experience than me that knows how to handle this in R?
First you need to import the data to your global environment. Try the function read.table()
To name rows, try
(assuming your data.frame is named df):
rownames(df) <- df[, "geo"]
df <- df[, -1]
Well, your question is not that clear...
I assume you are trying to create a data.frame with named rows. If you look at the data.frame help you can see the parameter row.names description
NULL or a single integer or character string specifying a column to be used as row names, or a character or integer vector giving the row names for the data frame.
which means you can manually specify the row names when you create the data.frame or the column containing the names. The former can be achived as follows
d = data.frame(x=rnorm(10), # 10 random data normally distributed
y=rnorm(10), # 10 random data normally distributed
row.names=letters[1:10] # take the first 10 letters and use them as row header
)
while the latter is
d = data.frame(x=rnorm(10), # 10 random data normally distributed
y=rnorm(10), # 10 random data normally distributed
r=letters[1:10], # take the first 10 letters
row.names=3 # the column with the row headers is the 3rd
)
If you are reading the data from a file I will assume you are using the command read.table. Many of its parameters are the same of data.frame, in particular you will find that the row.headers parameter works the same way:
a vector of row names. This can be a vector giving the actual row names, or a single number giving the column of the table which contains the row names, or character string giving the name of the table column containing the row names.
Finally, if you have already read the data.frame and you want to change the row names, Pierre's answer is your solution