[英]How to Print “Pretty” String Output in Python
我有一個dicts列表,其中包含來自sql查詢的字段classid,dept,coursenum,area和title。 我想以人類可讀的格式輸出值。 我在每個頂部想到一個Column標題,然后在每個列中考慮approrpiate輸出,即:
CLASSID DEPT COURSE NUMBER AREA TITLE
foo bar foo bar foo
yoo hat yoo bar hat
(顯然標准對齊/間距)
我如何在python中實現這一目標?
標准Python字符串格式化可能就足夠了。
# assume that your data rows are tuples
template = "{0:8}|{1:10}|{2:15}|{3:7}|{4:10}" # column widths: 8, 10, 15, 7, 10
print template.format("CLASSID", "DEPT", "COURSE NUMBER", "AREA", "TITLE") # header
for rec in your_data_source:
print template.format(*rec)
要么
# assume that your data rows are dicts
template = "{CLASSID:8}|{DEPT:10}|{C_NUM:15}|{AREA:7}|{TITLE:10}" # same, but named
print template.format( # header
CLASSID="CLASSID", DEPT="DEPT", C_NUM="COURSE NUMBER",
AREA="AREA", TITLE="TITLE"
)
for rec in your_data_source:
print template.format(**rec)
使用對齊,填充和精確格式說明符來獲得最佳結果。
class TablePrinter(object):
"Print a list of dicts as a table"
def __init__(self, fmt, sep=' ', ul=None):
"""
@param fmt: list of tuple(heading, key, width)
heading: str, column label
key: dictionary key to value to print
width: int, column width in chars
@param sep: string, separation between columns
@param ul: string, character to underline column label, or None for no underlining
"""
super(TablePrinter,self).__init__()
self.fmt = str(sep).join('{lb}{0}:{1}{rb}'.format(key, width, lb='{', rb='}') for heading,key,width in fmt)
self.head = {key:heading for heading,key,width in fmt}
self.ul = {key:str(ul)*width for heading,key,width in fmt} if ul else None
self.width = {key:width for heading,key,width in fmt}
def row(self, data):
return self.fmt.format(**{ k:str(data.get(k,''))[:w] for k,w in self.width.iteritems() })
def __call__(self, dataList):
_r = self.row
res = [_r(data) for data in dataList]
res.insert(0, _r(self.head))
if self.ul:
res.insert(1, _r(self.ul))
return '\n'.join(res)
並在使用中:
data = [
{'classid':'foo', 'dept':'bar', 'coursenum':'foo', 'area':'bar', 'title':'foo'},
{'classid':'yoo', 'dept':'hat', 'coursenum':'yoo', 'area':'bar', 'title':'hat'},
{'classid':'yoo'*9, 'dept':'hat'*9, 'coursenum':'yoo'*9, 'area':'bar'*9, 'title':'hathat'*9}
]
fmt = [
('ClassID', 'classid', 11),
('Dept', 'dept', 8),
('Course Number', 'coursenum', 20),
('Area', 'area', 8),
('Title', 'title', 30)
]
print( TablePrinter(fmt, ul='=')(data) )
產生
ClassID Dept Course Number Area Title
=========== ======== ==================== ======== ==============================
foo bar foo bar foo
yoo hat yoo bar hat
yooyooyooyo hathatha yooyooyooyooyooyooyo barbarba hathathathathathathathathathat
如果你想保持簡單,你可以簡單地將字符串左對齊到一定數量的字符:
print string1.ljust(20) + string2.ljust(20)
這個函數使列表理解有點極端,但它以最佳性能完成了你正在尋找的東西:
算法:
row_collection:iterables列表(dicts / sets / lists),每個包含一行的數據。
key_list:list,指定從每行讀取哪些鍵/索引以形成列。
def getPrintTable(row_collection, key_list, field_sep=' '*4):
return '\n'.join([field_sep.join([str(row[col]).ljust(width)
for (col, width) in zip(key_list, [max(map(len, column_vector))
for column_vector in [ [v[k]
for v in row_collection if k in v]
for k in key_list ]])])
for row in row_collection])
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