Sometimes if you create a dataframe with rbind() in R and then save it by write.table() to a text file, all entries (numeric too) will be put in double quotes.
To remove them one can use the following Python3 script, which is especially useful if you have a lot of files.
import os
filePath = "/path/to/dir"
arr = os.listdir(filePath)
for fileName in arr:
print(fileName)
if ".txt" in fileName:
fl = open(filePath+fileName, 'r')
dat = fl.read()
fl.close()
dat2 = dat.replace("\"", "")
fl2 = open(filePath+fileName, 'w')
fl2.write(dat2)
fl2.close()