|
| 1 | +# Numpy Data Types |
| 2 | +In NumPy, data types play a crcial role in representing and manipulating numerical data. |
| 3 | + |
| 4 | +Numpy supports the following data types: |
| 5 | + |
| 6 | +- `i` - integer |
| 7 | +- `b` - boolean |
| 8 | +- `u` - unsigned integer |
| 9 | +- `f` - float |
| 10 | +- `c` - complex float |
| 11 | +- `m` - timedelta |
| 12 | +- `M` - datetime |
| 13 | +- `O` - object |
| 14 | +- `S` - string |
| 15 | +- `U` - unicode string |
| 16 | + |
| 17 | + |
| 18 | +_Referred from: W3schools_ |
| 19 | + |
| 20 | +## dtype() Function |
| 21 | +The `dtype()` function returns the type of the NumPy array object. |
| 22 | + |
| 23 | +Example 1 |
| 24 | +``` python |
| 25 | + import numpy as np |
| 26 | + |
| 27 | + arr = np.array([1, 2, 3, 4]) |
| 28 | + |
| 29 | + print(arr.dtype) |
| 30 | + |
| 31 | + # Output: int64 |
| 32 | +``` |
| 33 | + |
| 34 | +Example 2 |
| 35 | +``` python |
| 36 | + import numpy as np |
| 37 | + |
| 38 | + arr = np.array(['apple', 'banana', 'cherry']) |
| 39 | + |
| 40 | + print(arr.dtype) |
| 41 | + |
| 42 | + # Output: <U6 |
| 43 | +``` |
| 44 | +## Example for integer type |
| 45 | +The NumPy integer array can be defined in two ways. |
| 46 | + |
| 47 | +Way 1: Using function `int_()` |
| 48 | +``` python |
| 49 | + import numpy as np |
| 50 | + |
| 51 | + arr = np.int_([2,4,6]) |
| 52 | + # Size: int8, int16, int32, int64 |
| 53 | + |
| 54 | + print(arr.dtype()) |
| 55 | + |
| 56 | + # Output: int64 |
| 57 | +``` |
| 58 | + |
| 59 | +Way 2: Using `dtype()` |
| 60 | +``` python |
| 61 | + import numpy as np |
| 62 | + |
| 63 | + arr = np.array([2,4,6], dtype='i4') |
| 64 | + # Size: i1, i2, i4, i8 |
| 65 | + |
| 66 | + print(arr.dtype) |
| 67 | + |
| 68 | + # Output: int32 |
| 69 | +``` |
| 70 | + |
| 71 | +Note: `np.intc()` has the same function as `int32()`. |
| 72 | +## Example for float type |
| 73 | + |
| 74 | +Way 1: Using function `float_()` |
| 75 | +``` python |
| 76 | + import numpy as np |
| 77 | + |
| 78 | + arr = np.float_(1) |
| 79 | + # Size: float8, float16, float32, float64 |
| 80 | + |
| 81 | + print(arr) |
| 82 | + print(arr.dtype()) |
| 83 | + |
| 84 | + # Output: |
| 85 | + # 1.0 |
| 86 | + # float64 |
| 87 | +``` |
| 88 | + |
| 89 | +Way 2: Using `dtype()` |
| 90 | +``` python |
| 91 | + import numpy as np |
| 92 | + |
| 93 | + arr = np.array([2,4,6], dtype='f4') |
| 94 | + # Size: f1, f2, f4, f8 |
| 95 | + |
| 96 | + print(arr) |
| 97 | + print(arr.dtype) |
| 98 | + |
| 99 | + # Output: |
| 100 | + # [1. 2. 3. 4.] |
| 101 | + # float32 |
| 102 | +``` |
| 103 | + |
| 104 | +Note: `np.single()` has the same function as `float32()`. |
| 105 | + |
| 106 | +## Example for boolean type |
| 107 | + |
| 108 | +``` python |
| 109 | + import numpy as np |
| 110 | + |
| 111 | + x = np.bool_(1) |
| 112 | + |
| 113 | + print(x) |
| 114 | + print(x.dtype) |
| 115 | + |
| 116 | + # Output: |
| 117 | + # True |
| 118 | + # bool |
| 119 | +``` |
| 120 | +## Example for unsigned integer type |
| 121 | + |
| 122 | +``` python |
| 123 | + import numpy as np |
| 124 | + |
| 125 | + x = np.uintc(1) |
| 126 | + |
| 127 | + print(x) |
| 128 | + print(x.dtype) |
| 129 | + |
| 130 | + # Output: |
| 131 | + # 1 |
| 132 | + # uint32 |
| 133 | +``` |
| 134 | + |
| 135 | +## Example for complex type |
| 136 | +Complex type is a combination of real number + imaginary number. The `complex_()` is used to define the complex type NumPy object. |
| 137 | +``` python |
| 138 | + import numpy as np |
| 139 | + |
| 140 | + x = np.complex_(1) |
| 141 | + # Size: complex64, complex128 |
| 142 | + |
| 143 | + print(x) |
| 144 | + print(x.dtype) |
| 145 | + |
| 146 | + # Output: |
| 147 | + # (1+0j) |
| 148 | + # complex128 |
| 149 | +``` |
| 150 | + |
| 151 | +## Example for datetime type |
| 152 | +The `datetime64()` is used to define the date, month and year. |
| 153 | + |
| 154 | +``` python |
| 155 | + import numpy as np |
| 156 | + |
| 157 | + x = np.datetime64('2024-05') |
| 158 | + y = np.datetime64('2024-05-20') |
| 159 | + z = np.datetime64('2024') |
| 160 | + |
| 161 | + print(x,x.dtype) |
| 162 | + print(y,y.dtype) |
| 163 | + print(z,z.dtype) |
| 164 | + |
| 165 | + # Output: |
| 166 | + # 2024-05 datetime64[M] |
| 167 | + # 2024-20-05 datetime64[D] |
| 168 | + # 2024 datetime64[Y] |
| 169 | +``` |
| 170 | + |
| 171 | +## Example for string type |
| 172 | +``` python |
| 173 | + import numpy as np |
| 174 | + |
| 175 | + arr = np.str_("roopa") |
| 176 | + |
| 177 | + print(arr.dtype) |
| 178 | + |
| 179 | + # Output: <U5 |
| 180 | +``` |
| 181 | + |
| 182 | +## Example for object type |
| 183 | +``` python |
| 184 | + import numpy as np |
| 185 | + |
| 186 | + arr = np.object_([1, 2, 3, 4]) |
| 187 | + |
| 188 | + print(arr) |
| 189 | + print(arr.dtype) |
| 190 | + |
| 191 | + # Output: |
| 192 | + # [1, 2, 3, 4] |
| 193 | + # object |
| 194 | +``` |
| 195 | +## Example for unicode string type |
| 196 | +``` python |
| 197 | + import numpy as np |
| 198 | + |
| 199 | + arr = np.array(['apple', 'banana', 'cherry']) |
| 200 | + |
| 201 | + print(arr.dtype) |
| 202 | + |
| 203 | + # Output: <U6 |
| 204 | +``` |
| 205 | +## Example for timedelta type |
| 206 | +The `timedelta64()` used to find the difference between the `datetime64()`. The arguments for timedelta64 are a number, to represent the number of units, and a date/time unit, such as (D)ay, (M)onth, (Y)ear, (h)ours, (m)inutes, or (s)econds. The timedelta64 data type also accepts the string “NAT” in place of the number for a “Not A Time” value. |
| 207 | + |
| 208 | +``` python |
| 209 | + import numpy as np |
| 210 | + |
| 211 | + x = np.datetime64('2024-05-20') |
| 212 | + y = np.datetime64('2023-05-20') |
| 213 | + res = x - y |
| 214 | + |
| 215 | + print(res) |
| 216 | + print(res.dtype) |
| 217 | + |
| 218 | + # Output: |
| 219 | + # 366 days |
| 220 | + # timedelta64[D] |
| 221 | +``` |
| 222 | +## Additional Data Type (`longdouble`) |
| 223 | +`longdouble` is a data type that provides higher precision than the standard double-precision floating-point (`float64`) type. |
| 224 | + |
| 225 | +``` python |
| 226 | + import numpy as np |
| 227 | + |
| 228 | + arr = np.longdouble([1.222222, 4.44, 45.55]) |
| 229 | + |
| 230 | + print(arr, arr.dtype) |
| 231 | + |
| 232 | + # Output: |
| 233 | + # [1.222222 4.44 45.55] float128 |
| 234 | +``` |
| 235 | + |
| 236 | +# Data Type Conversion |
| 237 | +`astype()` function is used to the NumPy object from one type to another type. |
| 238 | + |
| 239 | +It creates a copy of the array and allows to specify the data type of our choice. |
| 240 | + |
| 241 | +## Example 1 |
| 242 | + |
| 243 | +``` python |
| 244 | + import numpy as np |
| 245 | + |
| 246 | + x = np.array([1.2, 3.4, 5.6]) |
| 247 | + y = x.astype(int) |
| 248 | + |
| 249 | + print(y,y.dtype) |
| 250 | + |
| 251 | + # Output: |
| 252 | + # [1 3 5] int64 |
| 253 | +``` |
| 254 | + |
| 255 | +## Example 2 |
| 256 | + |
| 257 | +``` python |
| 258 | + import numpy as np |
| 259 | + |
| 260 | + x = np.array([1, 3, 0]) |
| 261 | + y = x.astype(bool) |
| 262 | + |
| 263 | + print(y,y.dtype) |
| 264 | + |
| 265 | + # Output: |
| 266 | + # [True True False] bool |
| 267 | +``` |
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