CLN: modernize string formatting (#22553)

Author: jbrockmendel

pandas/_libs/algos_common_helper.pxi.in

@@ -55,8 +55,9 @@ cpdef map_indices_{{name}}(ndarray[{{c_type}}] index):
 
  Better to do this with Cython because of the enormous speed boost.
  """
- cdef Py_ssize_t i, length
- cdef dict result = {}
+ cdef:
+ Py_ssize_t i, length
+ dict result = {}
 
  length = len(index)
 

pandas/_libs/parsers.pyx

@@ -29,7 +29,7 @@ cdef extern from "Python.h":
 
 import numpy as np
 cimport numpy as cnp
-from numpy cimport ndarray, uint8_t, uint64_t, int64_t
+from numpy cimport ndarray, uint8_t, uint64_t, int64_t, float64_t
 cnp.import_array()
 
 from util cimport UINT64_MAX, INT64_MAX, INT64_MIN
@@ -694,7 +694,7 @@ cdef class TextReader:
  if ptr == NULL:
  if not os.path.exists(source):
  raise compat.FileNotFoundError(
- 'File %s does not exist' % source)
+ 'File {source} does not exist'.format(source=source))
  raise IOError('Initializing from file failed')
 
  self.parser.source = ptr
@@ -772,9 +772,10 @@ cdef class TextReader:
 
  if name == '':
  if self.has_mi_columns:
- name = 'Unnamed: %d_level_%d' % (i, level)
+ name = ('Unnamed: {i}_level_{lvl}'
+ .format(i=i, lvl=level))
  else:
- name = 'Unnamed: %d' % i
+ name = 'Unnamed: {i}'.format(i=i)
  unnamed_count += 1
 
  count = counts.get(name, 0)
@@ -849,8 +850,8 @@ cdef class TextReader:
  # 'data has %d fields'
  # % (passed_count, field_count))
 
- if self.has_usecols and self.allow_leading_cols and \
- not callable(self.usecols):
+ if (self.has_usecols and self.allow_leading_cols and
+ not callable(self.usecols)):
  nuse = len(self.usecols)
  if nuse == passed_count:
  self.leading_cols = 0
@@ -1027,17 +1028,19 @@ cdef class TextReader:
 
  if self.table_width - self.leading_cols > num_cols:
  raise ParserError(
- "Too many columns specified: expected %s and found %s" %
- (self.table_width - self.leading_cols, num_cols))
+ "Too many columns specified: expected {expected} and "
+ "found {found}"
+ .format(expected=self.table_width - self.leading_cols,
+ found=num_cols))
 
  results = {}
  nused = 0
  for i in range(self.table_width):
  if i < self.leading_cols:
  # Pass through leading columns always
  name = i
- elif self.usecols and not callable(self.usecols) and \
- nused == len(self.usecols):
+ elif (self.usecols and not callable(self.usecols) and
+ nused == len(self.usecols)):
  # Once we've gathered all requested columns, stop. GH5766
  break
  else:
@@ -1103,7 +1106,7 @@ cdef class TextReader:
  col_res = _maybe_upcast(col_res)
 
  if col_res is None:
- raise ParserError('Unable to parse column %d' % i)
+ raise ParserError('Unable to parse column {i}'.format(i=i))
 
  results[i] = col_res
 
@@ -1222,8 +1225,8 @@ cdef class TextReader:
  elif dtype.kind == 'U':
  width = dtype.itemsize
  if width > 0:
- raise TypeError("the dtype %s is not "
- "supported for parsing" % dtype)
+ raise TypeError("the dtype {dtype} is not "
+ "supported for parsing".format(dtype=dtype))
 
  # unicode variable width
  return self._string_convert(i, start, end, na_filter,
@@ -1241,12 +1244,12 @@ cdef class TextReader:
  return self._string_convert(i, start, end, na_filter,
  na_hashset)
  elif is_datetime64_dtype(dtype):
- raise TypeError("the dtype %s is not supported "
+ raise TypeError("the dtype {dtype} is not supported "
  "for parsing, pass this column "
- "using parse_dates instead" % dtype)
+ "using parse_dates instead".format(dtype=dtype))
  else:
- raise TypeError("the dtype %s is not "
- "supported for parsing" % dtype)
+ raise TypeError("the dtype {dtype} is not "
+ "supported for parsing".format(dtype=dtype))
 
  cdef _string_convert(self, Py_ssize_t i, int64_t start, int64_t end,
  bint na_filter, kh_str_t *na_hashset):
@@ -2058,7 +2061,7 @@ cdef kh_float64_t* kset_float64_from_list(values) except NULL:
  khiter_t k
  kh_float64_t *table
  int ret = 0
- cnp.float64_t val
+ float64_t val
  object value
 
  table = kh_init_float64()
@@ -2101,7 +2104,7 @@ cdef raise_parser_error(object base, parser_t *parser):
  Py_XDECREF(type)
  raise old_exc
 
- message = '%s. C error: ' % base
+ message = '{base}. C error: '.format(base=base)
  if parser.error_msg != NULL:
  if PY3:
  message += parser.error_msg.decode('utf-8')