I want to run a function over a loop and I want to store the outputs in different files, such that the filename contains the loop variable. Here is an example
for i in xrange(10):
f = open("file_i.dat",'w')
f.write(str(func(i))
f.close()
How can I do it in python?
Simply construct the file name with + and str. If you want, you can also use old-style or new-style formatting to do so, so the file name can be constructed as:
"file_" + str(i) + ".dat"
"file_%s.dat" % i
"file_{}.dat".format(i)
Note that your current version does not specify an encoding (you should), and does not correctly close the file in error cases (a with statement does that):
import io
for i in xrange(10):
with io.open("file_" + str(i) + ".dat", 'w', encoding='utf-8') as f:
f.write(str(func(i))
Use f = open("file_{0}.dat".format(i),'w'). Actually, you might want to use something like f = open("file_{0:02d}.dat".format(i),'w'), which will zero-pad the name to keep it at two digits (so you get "file_01" instead of "file_1", which can be nice for sorting later). See the documentation.
Concatenate the i variable to a string as follows:
f = open("file_"+str(i)+".dat","w")
OR
f = open("file_"+`i`+".dat","w") # (`i`) - These are backticks, not the quotes.
See here for other techniques available.
Try this:
for i in xrange(10):
with open('file_{0}.dat'.format(i),'w') as f:
f.write(str(func(i)))
f and the variable is inside the string quotes, surrounded by {}.
f"file_{i}.dat"range not xrangef.write(f'{func(i)}') or f.write(str(func(i)))def func(i):
return i**2
for i in range(10):
with open(f"file_{i}.dat", 'w') as f:
f.write(f'{func(i)}')
