input()
¶str
motako objektu bat bueltatzen dux = input('Idatzi zenbaki bat: ')
print(f'{x} {type(x)} motako objektu bat da')
Idatzi zenbaki bat: sdfhsdfhs zfhdf sdfhsdfhs zfhdf <class 'str'> motako objektu bat da
print()
¶str()
funtzioaren bidez, ondoren testu hoiek pantailatik erakusteko.help(print)
Help on built-in function print in module builtins: print(...) print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False) Prints the values to a stream, or to sys.stdout by default. Optional keyword arguments: file: a file-like object (stream); defaults to the current sys.stdout. sep: string inserted between values, default a space. end: string appended after the last value, default a newline. flush: whether to forcibly flush the stream.
sep
→ balioen artean gehitutako karattere katea (defektuz, hutsunea).end
→ amaieran gehitutako karaktere katea (defektuz, lerro berri bat).file
→ non idatzi (defektuz, irteera estandarra).flush
→ flushing-a behartu ala ez.Guk geure myprint()
funtzioa sor genezake:
import sys
def myprint(*args, sep=' ', end='\n', file=sys.stdout):
#print(type(args))
z = []
for x in args :
z.append(str(x))
file.write(sep.join(z) + end)
print('kaixo',123,[1,2,3],enumerate("aeiou"))
myprint('kaixo',123,[1,2,3],enumerate("aeiou"))
print('kaixo',123,[1,2,3],enumerate("aeiou"),sep='_|_',end='#\n')
myprint('kaixo',123,[1,2,3],enumerate("aeiou"),sep='_|_',end='#\n')
kaixo 123 [1, 2, 3] <enumerate object at 0x7f96480d65a0> kaixo 123 [1, 2, 3] <enumerate object at 0x7f96480d65a0> kaixo_|_123_|_[1, 2, 3]_|_<enumerate object at 0x7f96480d65a0># kaixo_|_123_|_[1, 2, 3]_|_<enumerate object at 0x7f96480d65a0>#
Mintegietan generadoreak zer diren ikusiko dugu... Oraingoz, adibide bat:
import sys
def myprint(*args, sep=' ', end='\n', file=sys.stdout):
file.write(sep.join(str(x) for x in args) + end)
print('kaixo',123,[1,2,3],enumerate("aeiou"))
myprint('kaixo',123,[1,2,3],enumerate("aeiou"))
print('kaixo',123,[1,2,3],enumerate("aeiou"),sep='_|_',end='#\n')
myprint('kaixo',123,[1,2,3],enumerate("aeiou"),sep='_|_',end='#\n')
kaixo 123 [1, 2, 3] <enumerate object at 0x7f96480bdbe0> kaixo 123 [1, 2, 3] <enumerate object at 0x7f96480bdbe0> kaixo_|_123_|_[1, 2, 3]_|_<enumerate object at 0x7f96480bdbe0># kaixo_|_123_|_[1, 2, 3]_|_<enumerate object at 0x7f96480bdf00>#
open()
metodoak fitxategi baten abstrakzioa errepresentatzen duen objektua sortzen du.f=open(...)
→ f.close()
help(open)
Help on built-in function open in module io: open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None) Open file and return a stream. Raise OSError upon failure. file is either a text or byte string giving the name (and the path if the file isn't in the current working directory) of the file to be opened or an integer file descriptor of the file to be wrapped. (If a file descriptor is given, it is closed when the returned I/O object is closed, unless closefd is set to False.) mode is an optional string that specifies the mode in which the file is opened. It defaults to 'r' which means open for reading in text mode. Other common values are 'w' for writing (truncating the file if it already exists), 'x' for creating and writing to a new file, and 'a' for appending (which on some Unix systems, means that all writes append to the end of the file regardless of the current seek position). In text mode, if encoding is not specified the encoding used is platform dependent: locale.getpreferredencoding(False) is called to get the current locale encoding. (For reading and writing raw bytes use binary mode and leave encoding unspecified.) The available modes are: ========= =============================================================== Character Meaning --------- --------------------------------------------------------------- 'r' open for reading (default) 'w' open for writing, truncating the file first 'x' create a new file and open it for writing 'a' open for writing, appending to the end of the file if it exists 'b' binary mode 't' text mode (default) '+' open a disk file for updating (reading and writing) 'U' universal newline mode (deprecated) ========= =============================================================== The default mode is 'rt' (open for reading text). For binary random access, the mode 'w+b' opens and truncates the file to 0 bytes, while 'r+b' opens the file without truncation. The 'x' mode implies 'w' and raises an `FileExistsError` if the file already exists. Python distinguishes between files opened in binary and text modes, even when the underlying operating system doesn't. Files opened in binary mode (appending 'b' to the mode argument) return contents as bytes objects without any decoding. In text mode (the default, or when 't' is appended to the mode argument), the contents of the file are returned as strings, the bytes having been first decoded using a platform-dependent encoding or using the specified encoding if given. 'U' mode is deprecated and will raise an exception in future versions of Python. It has no effect in Python 3. Use newline to control universal newlines mode. buffering is an optional integer used to set the buffering policy. Pass 0 to switch buffering off (only allowed in binary mode), 1 to select line buffering (only usable in text mode), and an integer > 1 to indicate the size of a fixed-size chunk buffer. When no buffering argument is given, the default buffering policy works as follows: * Binary files are buffered in fixed-size chunks; the size of the buffer is chosen using a heuristic trying to determine the underlying device's "block size" and falling back on `io.DEFAULT_BUFFER_SIZE`. On many systems, the buffer will typically be 4096 or 8192 bytes long. * "Interactive" text files (files for which isatty() returns True) use line buffering. Other text files use the policy described above for binary files. encoding is the name of the encoding used to decode or encode the file. This should only be used in text mode. The default encoding is platform dependent, but any encoding supported by Python can be passed. See the codecs module for the list of supported encodings. errors is an optional string that specifies how encoding errors are to be handled---this argument should not be used in binary mode. Pass 'strict' to raise a ValueError exception if there is an encoding error (the default of None has the same effect), or pass 'ignore' to ignore errors. (Note that ignoring encoding errors can lead to data loss.) See the documentation for codecs.register or run 'help(codecs.Codec)' for a list of the permitted encoding error strings. newline controls how universal newlines works (it only applies to text mode). It can be None, '', '\n', '\r', and '\r\n'. It works as follows: * On input, if newline is None, universal newlines mode is enabled. Lines in the input can end in '\n', '\r', or '\r\n', and these are translated into '\n' before being returned to the caller. If it is '', universal newline mode is enabled, but line endings are returned to the caller untranslated. If it has any of the other legal values, input lines are only terminated by the given string, and the line ending is returned to the caller untranslated. * On output, if newline is None, any '\n' characters written are translated to the system default line separator, os.linesep. If newline is '' or '\n', no translation takes place. If newline is any of the other legal values, any '\n' characters written are translated to the given string. If closefd is False, the underlying file descriptor will be kept open when the file is closed. This does not work when a file name is given and must be True in that case. A custom opener can be used by passing a callable as *opener*. The underlying file descriptor for the file object is then obtained by calling *opener* with (*file*, *flags*). *opener* must return an open file descriptor (passing os.open as *opener* results in functionality similar to passing None). open() returns a file object whose type depends on the mode, and through which the standard file operations such as reading and writing are performed. When open() is used to open a file in a text mode ('w', 'r', 'wt', 'rt', etc.), it returns a TextIOWrapper. When used to open a file in a binary mode, the returned class varies: in read binary mode, it returns a BufferedReader; in write binary and append binary modes, it returns a BufferedWriter, and in read/write mode, it returns a BufferedRandom. It is also possible to use a string or bytearray as a file for both reading and writing. For strings StringIO can be used like a file opened in a text mode, and for bytes a BytesIO can be used like a file opened in a binary mode.
mode
¶Character | Meaning |
---|---|
r |
open for reading (default) |
w |
open for writing, truncating the file first |
x |
open for exclusive creation, failing if the file already exists |
a |
open for writing, appending to the end of the file if it exists |
b |
binary mode |
t |
text mode (default) |
+ |
open for updating (reading and writing) |
f = open("MyText.txt",encoding="utf8")
print(type(f))
f.close()
<class '_io.TextIOWrapper'>
f = open("MyText.txt","rt",encoding="utf8")
print(type(f))
f.close()
<class '_io.TextIOWrapper'>
f = open("MyText.txt","rb")
print(type(f))
f.close()
<class '_io.BufferedReader'>
with
sententzia¶Errekurtsoak (adibidez, fitxategiak) erabiliak diren kasuetan, with
sententziako context manager -a errekurtsoen kudeaketaz (hasieratu/ireki, amaierazi/itxi) arduratuko da:
with <context manager> as x :
# x erabili
...
...
# with sententzia amaitzean, x errekurtsoa itxiko da
Fitxategiak euren buruen context manager -ak direnez, with sententziarekin erabil daitezke:
with open("MyText.txt",encoding="utf8") as f :
print(type(f))
<class '_io.TextIOWrapper'>
'\n'
-z amaitutako karaktere kateakwith open("MyText.txt",encoding="utf8") as f :
for x in f :
#print(x,end='')
print(x.rstrip())
Hau testu fitxategi bat da Bi ilara ditu Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko
with open("MyText.txt",encoding="utf8") as f :
for i,x in enumerate(f) :
print(f'{i}: {x.rstrip()}')
0: Hau testu fitxategi bat da 1: Bi ilara ditu 2: Ez, bi ez, hiru jakiña! 3: Laugarren bat amaitzeko
with open("MyText.txt",encoding="utf8") as f :
print(list(f))
['Hau testu fitxategi bat da\n', 'Bi ilara ditu\n', 'Ez, bi ez, hiru jakiña!\n', 'Laugarren bat amaitzeko']
with open("MyText.txt",encoding="utf8") as f :
print(*f,sep='')
Hau testu fitxategi bat da Bi ilara ditu Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko
with open("MyText.txt",encoding="utf8") as f :
for i in range(3):
print('-'*10,i,'-'*10)
print(*f,sep='')
---------- 0 ---------- Hau testu fitxategi bat da Bi ilara ditu Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko ---------- 1 ---------- ---------- 2 ----------
with open("MyText.txt",encoding="utf8") as f :
for x in f :
print('-'*30)
print(x,end='')
print('-'*30)
break
print(*f,sep='')
------------------------------ Hau testu fitxategi bat da ------------------------------ Bi ilara ditu Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko
Demagun fitxategi baten lehenengo n
ilarak goiburua direla:
n = 3
with open("MyText.txt",encoding="utf8") as f :
print('-'*10,'GOIBURUA','-'*10)
i = 0
for x in f :
print(x,end='')
i += 1
if i == n :
break
print('-'*30)
print(*f,sep='')
---------- GOIBURUA ---------- Hau testu fitxategi bat da Bi ilara ditu Ez, bi ez, hiru jakiña! ------------------------------ Laugarren bat amaitzeko
Kontuz f
fitxategia beste objektu bati ematearekin zeharkatze partzial bat egiteko.
n = 2
with open("MyText.txt",encoding="utf8") as f :
print('-'*10,'GOIBURUA','-'*10)
for i,x in enumerate(f,1) :
print(x,end='')
if i == n :
break
print('-'*30)
print(*f,sep='')
---------- GOIBURUA ---------- Hau testu fitxategi bat da Bi ilara ditu ------------------------------ Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko
n = 2
with open("MyText.txt",encoding="utf8") as f :
print('-'*10,'GOIBURUA','-'*10)
for x,_ in zip(f,range(n)) :
print(x,end='')
print('-'*30)
print(*f,sep='')
---------- GOIBURUA ---------- Hau testu fitxategi bat da Bi ilara ditu ------------------------------ Laugarren bat amaitzeko
n = 2
with open("MyText.txt",encoding="utf8") as f :
print('-'*10,'GOIBURUA','-'*10)
for _,x in zip(range(n),f) :
print(x,end='')
print('-'*30)
print(*f,sep='')
with open("MyText.txt",encoding="utf8") as f :
z = list(f)
print('-'*10,'GOIBURUA','-'*10)
print(*z[:n],sep='',end='')
print('-'*30)
print(*z[n:],sep='',end='')
---------- GOIBURUA ---------- Hau testu fitxategi bat da Bi ilara ditu ------------------------------ Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko ---------- GOIBURUA ---------- Hau testu fitxategi bat da Bi ilara ditu ------------------------------ Ez, bi ez, hiru jakiña! Laugarren bat amaitzeko
f.read(size=-1)
→ fitxategi osoa irakurri (edo size
byte)f.readline(size=-1)
→ fitxategiaren lerro bat irakurri (edo size
byte)f.readlines(hint=-1)
→ lerro guztiak zerrenda batean bueltatu (gehienez hint
byte)f.write(text)
→ text
karaktere katea idatzif.writelines(lines)
→ lines karaktere kate segidako elementuak idatzif.seek(offset, whence=0,)
→ fitxategi baten posizio konkretu batean kokatzekof.close()
→ fitxategia itxiGOGORATU: print()
metodoa ere erabil dezakegu write()
ordez
print(...,file=f)
sep=...
end=...
repr
eta eval
¶eval(source, globals=None, locals=None)
→ python-eko kodea (karaktere katea) ebaluatu (exekutatu)repr(obj)
→ obj
objektuaren errepresentazio kanonikoa (karaktere kate gisa) bueltaturepr(obj)
≠ str(obj)
eval(repr(obj)) == obj
eval('1+2')
3
z = eval('[1,2,3]')
print(z)
[1, 2, 3]
eval('z + [4,5,6]')
[1, 2, 3, 4, 5, 6]
#kontuz...
#eval('kaixo')
eval("'kaixo'")
eval('"kaixo"')
'kaixo'
eval("['a','e','i','o','u']")
['a', 'e', 'i', 'o', 'u']
print(repr([1,2,3]))
repr([1,2,3])
[1, 2, 3]
'kaixo'
z=list(range(10))
print(z)
print(repr(z))
print(eval(repr(z)) == z , eval(repr(z)) is z)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] True False
h = {1:"kaixo" , 2:[1,2,3] , 3:(5,6,7)}
print(h)
print(repr(h))
print(eval(repr(h)) == h)
{1: 'kaixo', 2: [1, 2, 3], 3: (5, 6, 7)} {1: 'kaixo', 2: [1, 2, 3], 3: (5, 6, 7)} True
Zein da str()
eta repr()
arteko ezberdintasuna?
for x in 12, 12.45, True, "kaixo", [1,2,3], [1,2,3,"kaixo"], (1,2,3), {1:2,3:4}, [1,2,3,(4,5,[6,7,{1:2,3:4}])] :
if str(x)==repr(x) :
print('OK' , type(x))
else :
print(f'WARNING: str={str(x)} repr={repr(x)}',)
z = [1,23,3,'kaixo']
print(z)
OK <class 'int'> OK <class 'float'> OK <class 'bool'> WARNING: str=kaixo repr='kaixo' OK <class 'list'> OK <class 'list'> OK <class 'tuple'> OK <class 'dict'> OK <class 'list'> [1, 23, 3, 'kaixo']
A = [[1,2,3],[4,5,6]]
B = eval(repr(A))
print(A)
print(B)
[[1, 2, 3], [4, 5, 6]] [[1, 2, 3], [4, 5, 6]]
eval(repr(o))
egitean o
objectuaren balioa mantenduko da, ez bere egitura
z = [1,2,3]
zz = [z,z,z]
print(str(zz))
print(repr(zz))
x = eval(repr(zz))
print(zz == x)
print(zz[0] is zz[1], x[0] is x[1])
[[1, 2, 3], [1, 2, 3], [1, 2, 3]] [[1, 2, 3], [1, 2, 3], [1, 2, 3]] True True False
Ikusi kodea Python Tutor-en
z = [1,200,3,(4,5,[6,7,{1:'bat',3:'hiru'}])]
with open('MyData.txt','wt',encoding='utf8') as f :
f.write(repr(z))
with open('MyData.txt','rt',encoding='utf8') as f :
x = eval(f.read())
print(x)
[1, 200, 3, (4, 5, [6, 7, {1: 'bat', 3: 'hiru'}])]
print(z)
print(x)
print(z==x,z is x)
[1, 200, 3, (4, 5, [6, 7, {1: 'bat', 3: 'hiru'}])] [1, 200, 3, (4, 5, [6, 7, {1: 'bat', 3: 'hiru'}])] True False
Bi funtzio sor ditzakegu...
def savetxt(obj,filename,encoding='utf8'):
with open(filename,'wt',encoding=encoding) as f :
f.write(repr(obj))
def loadtxt(filename,encoding='utf8'):
with open(filename,'rt',encoding=encoding) as f :
return eval(f.read())
z = {1:'bat',2:'bi',3:['???',56,7,"XXXXXXXXXXXX"]}
savetxt(z,'MyData.txt')
loadtxt('MyData.txt') == z
True
Objektu bat baina gehiago gorde nahi badugu, egitura bakarrean (nkote batetan adibidez) gorde ditzakegu...
a = [1,2,3,(4,5,[6,7,{1:'bat',3:'hiru'}])]
b = {1:'bat',2:'bi',3:['???',56,7]}
savetxt((a,b),'MyData.txt')
x,y = loadtxt('MyData.txt')
a == x and b == y
True
pickle
modulua¶pickle.dump(obj, file)
→ objektua fitxategian idatzipickle.load(file)
→ fitxategitik objektu bat irakurrifile
: modu bitarrean idatzi/irakurri daitekeen fitxategiaimport pickle
a = [1,2,3,(4,5,[6,7,{1:'bat',3:'hiru'}])]
b = {1:'bat',2:'bi',3:['???',56,7]}
with open('MyData.dat','wb') as f :
pickle.dump(a,f)
pickle.dump(b,f)
with open('MyData.dat','rb') as f :
x = pickle.load(f)
y = pickle.load(f)
a == x and b == y
True
Berriro ere, bi funtzio sor ditzakegu...
import pickle
def savebin(obj,filename):
with open(filename,'wb') as f :
pickle.dump(obj,f)
def loadbin(filename):
with open(filename,'rb') as f :
return pickle.load(f)
a = [1,2,3,(4,5,[6,7,{1:'bat',3:'hiru'}])]
b = {1:'bat',2:'bi',3:['???',56,7]}
savebin((a,b),'MyData.dat')
x,y = loadbin('MyData.dat')
a == x and b == y
True
Kontuz generadoreekin (enumerate
, zip
, ...)
print(repr(enumerate("aeiou")))
#eval(repr(enumerate("aeiou")))
print(repr(zip("aeiou",range(10))))
#eval(repr(zip("aeiou",range(10))))
a = enumerate("aeiou")
savebin(a,'MyData.dat')
b= loadbin('MyData.dat')
print(*a)
print(*b)
print(a == b , enumerate("aeiou") == enumerate("aeiou"))
print(enumerate("aeiou") == enumerate("aeiou"))
print(list(enumerate("aeiou")) == list(enumerate("aeiou")))
print(zip("aeiou",range(10)) == zip("aeiou",range(10)))
print(list(zip("aeiou",range(10))) == list(zip("aeiou",range(10))))