str1 = ["is" , "first"]
str2 = ["was" , "second"]
str3 = "he is doing his first year graduation"
for i in RANGE(len(str1)):
str4 = str3.replace(str1[i],str2[i])
Due to the immutable property only the second change ("first" to "second"). How can i make both changes together. Actually I have a huge size of string. I'm new to python, please help me
Simply assign the last line to str3:
str1 = ["is" , "first"]
str2 = ["was" , "second"]
str3 = "he is doing his first year graduation"
for i in range(len(str1)):
str3 = str3.replace(str1[i],str2[i])
print str3 # he was doing hwas second year graduation
Pay attention that the is in the word "his" is also being replaced!
If you want an "exact" matching, use the regex module:
import re
str1 = ["is" , "first"]
str2 = ["was" , "second"]
str3 = "he is doing his first year graduation"
for i in range(len(str1)):
str3 = re.sub(r'\b{}\b'.format(str1[i]),str2[i], str3)
print str3 # he was doing his second year graduation
You could do it in one line by applying reduce and lambda:
ans = reduce(lambda n, (old, new): n.replace(old, new), zip(str1,str2), str3)
example:
>>> str1 = ["is", "first"]
>>> str2 = ["was", "second"]
>>> str3 = "he is doing his first year graduation"
>>> ans = reduce(lambda n, (old, new): n.replace(old, new), zip(str1,str2), str3)
>>> ans
'he was doing hwas second year graduation'
However, I suppose in your origin design "his" would become "hwas", so you might still need to use re.sub as suggested by others:
>>> import re
>>> ans = reduce(lambda n, (old, new): re.sub(r'\b{}\b'.format(old), new, n), zip(str1,str2), str3)
>>> ans
'he was doing his second year graduation'
izip() doesn't generate a list, so it should not be able to fit in reduce() function, right?
from itertools import izip; print(reduce(lambda x,y: x + "".join(y), izip("abc","123"), "")) prints a1b2c3an alternative to @alfasin's answer is to enumerate the list, this yields same end result! Also, note that str3 is overwritten in each iteration of the for loop, no str4variable used
str1 = ["is" , "first"]
str2 = ["was" , "second"]
str3 = "he is doing his first year graduation"
for idx, s in enumerate(str1):
str3 = str3.replace(s,str2[idx])
print str3 # he was doing hwas second year graduation
This is not an issue of immutability. You keep creating a new str4 with only the latest replace. You want to create str4 once, and update it a few times. For example
str1 = ["is", "first"]
str2 = ["was", "second"]
str3 = "he is doing his first year graduation"
str4 = str3
for i in range(len(str1)):
str4 = str4.replace(str1[i], str2[i])
You'll notice this has a bug where "his" becomes "hwas" (I assume that's a bug). You could use regexes to only match words, but you're likely better off using dictionaries.
Create a dictionary with {str1[i]:str2[i]} for each i. Then iterate through each word in str3 replacing it with its value in the dictionary.
