Day 7 python字典

今天我们要介绍的是python的字典，所谓的字典就是指将元素用{}包住并且元素是由一个键(key)配上一个值(value)所组合而成的，像是我们平常用的字典。

字典(dictionary)

以下我们介绍几个间单的字典例子。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(data)
print(data1)

首先我们先宣告字典的变数，可以使用{}来宣告。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(type(data))
print(type(data1))

可以使用type()去查询变数的型态。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
for i in data:
    print(i)
for j in data1:
    print(j)

可以使用FOR回圈来抓取字典里面的key，可以看得抓出来资料是key而不是value。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
for i in data:
    if i == "orange":
        print(i)
for j in data1:
    if j == "k":
        print(j)

可以使用条件判断去抓取想要的资料，但资料抓取的是key。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(data["watermelon"])
print(data1['b'])

由於字典是由一个key配一个value而如果想查询某个key对应哪个value就可以使用上述方法去抓取value的资料。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
for i in data:
    print(data[i])
for j in data1:
    print(data1[j])

如果要用FOR回圈查询所有的value则可使用这种方式抓取。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
for i in data:
    if data[i] >= 60:
        print(data[i])
for j in data1:
    if data1[j] >= 20:
        print(data1[j])

而如果要以value做条件判断则可以使用此种方法去做判断。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(data)
print(data1)
data["mango"] = 90
data1["y"] = 25
print(data)
print(data1)

对字典做增加的动做只需要将变数後面加上想要加的key且key的value就可以增加进字典里。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(data)
print(data1)
del data["apple"] 
del data1["z"] 
print(data)
print(data1)

如果要对字典做删除的动作，可以使用此方法将字典里的key跟value做删除的动作。

data = {"apple":50,"banana":40,"watermelon":78,"orange":43,"grape":63}
data1 = {"a":1,
        "b":2,
        "d":4,
        "z":26,
        "k":11}
print(data)
print(data1)
data["apple"] = 21 
data1["z"] = 16
print(data)
print(data1)

如果只是单纯的修改value，可以使用此种方法将value做修改而不用删除重新增加。