re.sub
function in module
re.
re.sub
example in
String
Pattern Matching
in the
Python Tutorial.
If the file
outfile.txt
does not exist,
the following program will create it.
If the file
outfile.txt
already exists,
the program will overwrite the contents of the file,
if the program has permission to do so.
"""
Output a copy of the input file,
with every negative integer parenthesized instead of with a negative sign.
"""
import sys
import re #regular expressions
infilename = "infile.txt"
outfilename = "outfile.txt"
try:
infile = open(infilename, "r") #read (the "r" is unnecessary)
except FileNotFoundError:
print(f"Sorry, could not find input file \"{infilename}\".")
sys.exit(1)
except PermissionError:
print(f"Sorry, no permission to open input file \"{infilename}\".")
sys.exit(1)
try:
outfile = open(outfilename, "w") #write
except PermissionError:
print(f"Sorry, no permission to open output file \"{outfilename}\".")
sys.exit(1)
for line in infile:
line = line.rstrip("\n") #Remove the trailing newline.
line = re.sub(r"-(\d+)", r"(\1)", line)
print(line, file = outfile)
outfile.close()
infile.close()
sys.exit(0)
import sys
import re #regular expressions
filename = "/usr/share/dict/words"
try:
lines = open(filename)
except FileNotFoundError:
print(f"Sorry, could not find file \"{filename}\".")
sys.exit(1)
except PermissionError:
print(f"Sorry, no permission to open file \"{filename}\".")
sys.exit(1)
for line in lines:
line = line.rstrip("\n") #Remove the trailing newline.
if re.search("i.*i.*i.*i", line, flags = re.IGNORECASE): #not "iiii"
print(line)
lines.close()
sys.exit(0)
antidisciplinarian Mississippi multimillionaire
#every line that has exactly 4 i's, no more and no less
if re.search("^[^i]*i[^i]*i[^i]*i[^i]*i[^i]*$", line, flags = re.IGNORECASE):
#every line that has exactly 4 i's, no more and no less
if re.search("^[^i]*(i[^i]*){4}$", line, flags = re.IGNORECASE):
/* part of a C program */
typedef struct {
char field1;
int field2;
double field3;
char * field4;
} stooge_t;
stooge_t stooge[] = {
1.11, 1, ’a’, "moe",
2.22, 2, ’b’, "larry",
3.33, 3, ’c’, "curly",
4.44, 4, ’d’, "shemp",
5.55, 5, ’e’, "Buster Keaton",
};
I typed the four columns in the wrong order.
"""
Output a copy of the input file,
with the columns in the correct order.
"""
import sys
import re #regular expressions
infilename = "infile.c"
outfilename = "outfile.c"
try:
infile = open(infilename)
except FileNotFoundError:
print(f"Sorry, could not find input file \"{infilename}\".")
sys.exit(1)
except PermissionError:
print(f"Sorry, no permission to open input file \"{infilename}\".")
sys.exit(1)
try:
outfile = open(outfilename, "w")
except PermissionError:
print(f"Sorry, no permission to open output file \"{outfilename}\".")
sys.exit(1)
for i, line in enumerate(infile, start = 1):
line = line.rstrip("\n") #Remove the trailing newline.
if 11 <= i <= 15:
line = re.sub(r'\s*(\S+),\s*(\S+),\s*(\S+),\s*(".*"),', "\t\\3, \\2, \\1, \\4", line)
print(line, file = outfile)
outfile.close()
infile.close()
sys.exit(0)
123-45-6789 123-45-6789 123 45 6789 123-45-6789 123456789 123-45-6789 SS Num 123-45-6789 123-45-6789 123-45-678 ???-??-???? 000-00-0oOl ???-??-????
"""
Normalize social security numbers.
"""
import sys
import re #regular expressions
infilename = "infile.txt"
try:
infile = open(infilename)
except FileNotFoundError:
print(f"Sorry, could not find input file \"{infilename}\".")
sys.exit(1)
except PermissionError:
print(f"Sorry, no permission to open input file \"{infilename}\".")
sys.exit(1)
for line in infile:
line = line.rstrip("\n") #Remove the trailing newline.
line = re.sub(r"\D", "", line) #Remove every non-digit.
if not re.search("^\d{9}$", line):
line = 9 * "?"
line = re.sub("(...)(..)(....)", r"\1-\2-\3", line) #or "(.{3})(.{2})(.{4})"
print(line)
infile.close()
sys.exit(0)
(201) 200-1800 (201) 200-1800 212-639-5555 (212) 639-5555 2013433434 (201) 343-3434 1-800-343-3434 (800) 343-3434 555-1212 (???) 555-1212 012-345-6789 (???) 345-6789 122-345-6789 (???) 345-6789 113-045-6789 (113) ???-???? 123-045-6789 (???) ???-????
"""
Translate a string (a word or sentence) from English into Pig Latin.
Example:
Read my open lips: "No new taxes!"
Eadray myay openway ipslay: "Onay ewnay axestay!"
"""
import sys
import re #regular expressions
#Rearrange the matched word into Pig Latin.
def rearrange(m):
assert type(m) == re.Match
word = m.group()
leadingConsonants = m.group(1)
rest = m.group(2) #the rest of the word
isupper = word and word[0].isupper()
if re.match(r"[aeiou]", word, flags = re.IGNORECASE):
leadingConsonants = "w"
pigLatinWord = rest + leadingConsonants + "ay"
if isupper:
pigLatinWord = pigLatinWord.capitalize()
return pigLatinWord
#Divide the matched word into the leading consonants and the rest of the word.
#Pass these two groups of characters to rearrange.
def divide(m):
assert type(m) == re.Match
word = m.group()
return re.sub(r"^([bcdfghjklmnpqrstvwxyz]*)(\w*)",
rearrange, word, flags = re.IGNORECASE)
#Pass each non-empty word in the user's string to divide.
s = input("Please type one or more words: ")
pigLatin = re.sub(r"\w+", divide, s)
print(pigLatin)
sys.exit(0)
Please type one or more words: Read my open lips: "No new taxes!" Eadray myay openway ipslay: "Onay ewnay axestay!"
import sys import re #regular expressions rows = [ ".....+...", "+......+.", "....+.+..", "+.+...+..", "...++.+.." ] for _ in range(2): rows = [re.sub(r"\+.*\+", lambda m: m.group().replace(".", "*"), row) for row in rows] rows = ["".join(row) for row in zip(*rows)] #Transpose the rows and columns. for row in rows: print(row) sys.exit(0)
.....+... +******+. *...+*+.. +*+***+.. ...++*+..